“One Country，Two Systems” is China's basic state policy to deal with both the relationship between Inland and Hong Kong or Macao and the relationship between Mainland China and Taiwan，both Hongkong and Macao Basic Law entitle the Special Administrative Region to enter into international agreements in some fields. Hongkong and Macao signed some BIT with foreign governments under the authorization from Chinese central government. When a host state government do not engage in a BIT with Hongkong or Macao but has a BIT with Chinese central government，or these two types of BIT overlap with each other，the question whether BIT signed by central government applies to Hongkong and Macao arises. The case Tza Yap Shum v. Peru and Sanum v. Laos reflect the question about the application of BIT signed by central government in Hongkong and Macao，the tribunal in both cases hold the affirmative opinion，the academic circles have both compliment and criticism. Strictly speaking，the application of Chinese BIT in Hongkong and Macao is absolutely not the question of treaty succession，but the extension of treaty's territorial scope，when the tribunal interprets the treaty they should take the parties' opinions into consideration，China should also clarify the territorial scope when revising BIT in the future.