Disclosed is a method for determining a rock soil parameter standard value. By adopting the method, the rock soil parameter mean confidence interval is narrower than a confidence interval obtained by a t distribution method, and the obtained standard value is closer to the real value. The method comprises the steps of performing random sampling with replacement on multiple groups of rock soil parameter test data respectively by adopting a nonparametric self-help method to obtain a standard value of a rock soil parameter, fitting the standard value of the rock soil parameter test data with the number of rock soil samples, the same mean and the sample standard deviation by using a function relation FORMULA to obtain a fitting formula: FORMULA. The method is suitable for determining the rock soil parameter standard value under different sample size conditions, is simple, and can effectively narrow the parameter mean confidence interval while ensuring the same confidence level, so that the standard value is closer to the real value.