The invention discloses a hydropower set vibration monitoring channel abnormity detection method based on condition identification. Historical vibration data of each measurement point is retrieved through a vibration monitoring protection device, and a normal threshold scope of a vibration signal of each measurement point is set according to engineering experiences; a present auxiliary contact point of a hydropower set and an operation state signal are detected through the vibration monitoring protection device, and the operation condition can be accurately determined; when the hydropower set is in different operation conditions, whether vibration values surpass a vibration signal normal threshold scope corresponding to each measurement point sensor is detected in real time, channel abnormity of the vibration signal can be sensitively reflected, including sensor abnormality and device sampling channel abnormality. The method is advantaged in that through only digging the historical vibration data and identifying the hydropower set operation condition, alarm for the channel not in the normal vibration signal threshold scope is carried out, channel self-check of a hydropower set vibration monitoring system is improved, and vibration monitoring and protection tripping reliability is improved.