To put it simply, cross-border e-commerce is the online purchase of goods from abroad, typically from merchants that operate in different countries, different jurisdictions, and even different languages.
This means that brands can sell and ship products directly to Chinese consumers, through special customs clearance regulations that are different from those of general trade. China’s CBEC pilot zones and their special customs clearance gateways enable them to do this.
International retailers and merchants can stock goods in their home countries or bonded warehouses in Hong Kong or Chinese free trade zones, reducing the inventory risk of exporting to China and stocking them in Chinese warehouses. This also eliminates the need for wholesalers or importers in the middle.

There are generally three legal ways for products to enter via cross-border e-commerce and it depends on where the warehouse is located.
Under UPU (universal postal union) postal shipping, different postal offices around the world collaborate to ship small personal packages across borders; in China, government-run China Post Group handles last mile delivery for cross-border postal shipping. Postal shipping corresponds to personal customs clearance, and products do not have to have import permits or registration filings. While most packages go through customs without a hitch, customs officials may inspect a small percentage of packages, which may be levied a postal tax of 15%, 30%, or 60%, depending on the product category.
Business Commercial shipping (often referred to as B2C imports) is a formal import e-commerce model that was introduced in 2016. Under this model, merchants who sell directly to Chinese consumers pre-register their products as B2C shipments and three types of information (order, payment, and delivery info) are provided to Chinese customs authorities before the packages arrive.
The bonded importing model involves the stocking of inventory in bonded warehouses in Hong Kong or free trade zones in mainland China, so as to facilitate the faster fulfillment of orders.
This drastically cuts down shipping and customs clearance times, but creates larger inventory risk in that merchants must be able to forecast customer demand to figure out how much inventory to stock.

For postal shipments, there should not be more than six items, and altogether the value of the items should not be more than 1,000 RMB.
However, if the shipment consists of just one item, then there is no limit on the value of that one item. Merchants should think carefully, however, if they want high-value items such as handbags to be handled by postal couriers.
Products cannot be on the list of banned items of either the national post office or China customs.
There is no requirement for the products to acquire import permit from the Chinese customs or registration filing. Retailers should provide details of the products and the recipient for customs declaration purposes.
The Positive List was introduced in April 2016, and the government designates certain items as eligible, and other items as ineligible.
Products not on the list need to have import permits, registration forms (e.g. nutrition products need to apply for CFDA permit for domestic circulation and sales) and other filings, which are pre-requisites for customs clearance certificates.
However, these requirements have not been enforced and all items are still regarded as personal items, though they are taxed under the Business Commercial tax rates.
Each transaction is limited to 5,000 RMB per order, and each person has an annual limit of 26,000 RMB. These limits were raised on November 21st, 2018 by the State Council.

For some brands/retailers, cross-border e-commerce is a stepping stone for those who want to test the market but eventually move to general trade, where they can stock inventory in China and set up offline retail operations.
For others, cross-border e-commerce can be a long-term solution for those who choose not to build out complete retail operations in China. Sometimes going through the general trade import channel is a major hassle.
For health & nutrition products, entering China through general trade requires an expensive and lengthy product registration process with the China Food & Drug Administration, which sometimes can take years.
For cosmetics products, entering China through general trade requires animal testing for product approval purposes, which many international cruelty-free brands refuse to do.
For other categories such as mom & baby or luxury products, consumers may prefer to purchase from abroad because of the prevalence of fake goods in China. Since China customs is cutting down on the gray-market daigou trade, cross-border e-commerce is likely to become more popular over time.