Abstract: The author used Microsoft Visual C++ 6.0 as development tool，combined the existing brain potential collector，to design a kind of event-related potential system which integrated signal evoking，collecting and processing. The main functions of the system included visual evoking，real time collecting and displaying of the brain electricity signal，processed pretreatment and wavelet multi- resolution analysis. Meanwhile，the system solved the problem of desynchrony of stimulation and collection. In stimulus modelity，the system provided two stimulation sequences，one was OddBall mode and the other was equal probability mode. In the practical application，carried out visual simulation to testees with OddBall mode， implemented data pretreatment and wavelet multi- resolution analysis， finally，the system extracted P300. It proves feasibility and effectiveness of the system in ERP research.

Key words: event-related potential（ERP）, wavelet-resolution analysis, P300, visual stimulation