A "backdoor" filing is from a multinational company headquartered in a country outside the Hague system, which takes advantage of its overseas subsidiaries to file the international application.

China ranked ninth in the number of international applications worldwide in 2018, growing 142 percent from a year earlier. 

However, among the top 20 applicants, China is the only one staying outside the Hague system, Lyu said. 

Li Yanjun, patent management director of the legal affairs department at Xiaomi Group, said: "Xiaomi commands its designs spread - from smartphones and the internet of things to Mi Look software design. 

"At Xiaomi, the IP of industrial designs has three backups: standardized management, entire process control and an application strategy." 

"When our IP team spots a competing product with a similar industrial design, it will use its veto power or urge the research and development team to make certain improvements to the structure of the product," Li said. "The structure determines the product's appearance. It is the embodiment of added value by the IP team."

Christophe Branchu, founder and creative director of JU&KE Creative Design Studio, said that Chinese brands are rising sharply and young generations in China are proud of domestic brands.

"Many brands, which appeared in Shenzhen years ago, are not only using a global design language to share stories abroad but integrating the local culture to create a Chinese design language," he said. 

"Now high-tech products are easy to export, but sometime soon fashion brands and designers will also expand overseas," he said.

China is taking steps to join the Hague Agreement.

For example, NIPA now is working on a draft amendment of the Patent Law, which extends the protection of an industrial design patent from 10 years to 15 years.

"We are expecting that to happen," said Lu Bei, senior consultant of P&G.