Microseismic is a useful technique applied to the fluid injecting front image and reservoir dynamic monitoring. The volume of the data is large as a result of continuous monitoring, and the break time of the microseismic events are unknown, and the manual picking will waste a long time, so the microseismic events need be automaticly detected by the computer. In this article, on the base of analysising the characters of background noise and some other correlating noise in the borehole environment are analysised, take long-to-short windows energy ratio as a basic method, combined with polarization analysis, deseign the polary-energy ratio method to detect the microseismic events, and this method is proved useful through the actual data. According to the regular of signal and noise of multi-channels, constrain the result of detection with the differences of arrive time among different geophones. Apply his method to whole set of microseismic monitor data, amount of microseismic events are picked automaticely and stably, got a good application effect.