Does the overseas economic and trade cooperation zone established by China in the "the Belt and Road" countries increase the technical complexity of China's export to the "the Belt and Road" countries? Using national panel data from 1992 to 2020, this paper empirically analyzes the impact of China's cooperation zones established in countries along the the Belt and Road on the complexity of China's export technology to countries along the the Belt and Road using the multi period DID method. The study found that the cooperation zone significantly improved the technical complexity of China's export to the "the Belt and Road" countries, and still passed the robustness test. The effect of this promotion is heterogeneous in host countries with different economic characteristics.