[Purpose/significance] The current research on knowledge exchange in technical Q&A communities is not perfect. This article uses data envelopment analysis method to study the efficiency of knowledge exchange in technical Q&A communities, and finds the differences and changing laws between different sectors to provide references for improving community management and improving the efficiency of knowledge exchange. [Method/process] Based on the construction of the knowledge exchange efficiency evaluation index system, 15 popular sections of the “OSCHINA” community were used as the research samples, and the static and dynamic efficiency values of the knowledge exchange are calculated and analyzed deeply based on the SBM model and the Malmquist index. [Result/conclusion] The average knowledge exchange efficiency among the 15 popular sections of the “OSCHINA” community is good, but the gap between the sections is large, and the overall knowledge exchange efficiency is on the rise trend, mainly because the technological progress change index increases 19.50%. The increasing rate indicates that technological revitalization is the main reason for the increase in the efficiency of knowledge exchange in the “OSCHINA” community, but a certain degree of mismanagement has occurred and the utilization of resources is low.