In the paper,the three method of diagnostic criteria in oil monitoring for wind turbines were discussed,which are respectivele normal distribution,lognormal distribution,cumulative distribution. The applications of the three methods to settings of threshold value of some information parameters in oil monitoring for wind turbines. were analyzed,and the processing results were respectively discussed. The results shows that the setting methods of diagnostic criteria based on the statistical methods can be used in oil monitoring for wind turbines. The research is helpful to improve the level of oil monitoring for wind turbines.