The Common System Requirements Analysis (CSRA) method in the avionics system design domain was presented in this paper. The CSRA method was improved from the Quality Function Deployment (QFD) method. The basic principle and the analysis steps of the CSRA were depicted. A practical case of the common avionics system requirements analysis and three proposals assessment was executed by adopting the CSRA method and its results. The case application showed the feasible and capability of the CSRA method on the design procedures of common avionics system of a multisystem, such as the Series Rotorcraft Unmanned Aerial System (SRUAS), which have several independent systems for different types of missions. The CSRA can enable the higher quality, lower cost, and shorter development period of the common avionics system.