Multi-band, multi-service and multi-modulation are new trends of GNSS development. Since novel modulation types like BOC/MBOC and multiplex techniques like (POCET, Interplex) of navigation signals have been utilized [1], the composite navigation performance is indeed improved. However, new challenges have arisen in the navigation signal quality monitoring area. Generally, common standard instruments, monitoring receiver and offline data analysis are three basic methods in signal quality monitoring [2-9], while the former two are considered to be less comprehensive and inflexible when dealing with new signal plans. An offline signal quality monitoring software of BDS with new signal plan based on (SDR) receiver is developed for flexible signal quality monitoring task in BDS construction. The paper, analyzes the software monitoring parameters like carrier phase and navigation data based on the conclusion of traditional signal quality monitoring parameters. Among them, the parameters like correlation loss, correlation peak, and carrier-code coherence are emphasized. Accordingly, the method of offline data analysis is given. Lastly, a signal quality test of modernized BDS is taken by employing the offline data analysis, and the results prove the effectiveness and practicability of this software.