[en] A new prototype system for bunch-by-bunch beam position measurement has been designed and built to monitor and analyse the beam loss in the Beijing Electron-Positron ColliderⅡ (BEPCⅡ) storage ring. The fast ADC is used to sample the analog signals from the beam position monitor, then the digital signal is processed further using programmable gate array (FPGA). The beam information can be obtained by means of bunch-by-bunch, such as bunch position, bunch current and bunch tune. Based on system monitoring and data analysis for long terms, as well as the dedicated machine experiments, it's relatively clear for operators to understand some trip events, especially the beam loss caused by the high-frequency cavity trip, tune drift and multiple bunch instability. The study proves that the system is very useful for the operation of accelerator. (authors)