The invention discloses a method for diagnosing a wind turbine main bearing fault based on temporal sequence clustering. The method comprises the following steps that step one, data (power data and main bearing temperature data) are collected, screened and calculated; step two, different power intervals are divided according power clustering, and all the power intervals are subjected to the flowing steps from step three to step seven; step three, fitness is evaluated; step four, good individual groups are selected; step five, a temperature datum line is obtained; step six, a temperature warning line is obtained; and step seven, the data are substituted for detection and early warning. According to the method, the wind turbine main bearing temperature is subjected temporal sequence power clustering and good individual group selection, whether a main bearing has an abnormal operation state or not is distinguished for diagnosis, the diagnosis result is reliable, the early warning capacity of the main bearing can be improved, manual troubleshooting is replaced by the data, targeted maintenance and defect elimination are achieved, the damage rate of the main bearing is decreased, the power generation rate and economic benefits of a wind turbine are increased.