In order to evaluate the performance of high-accuracy ring laser gyroscope (RLG) more precisely, a new method of analyzing the collecting data of high-accuracy dithered RLG using dynamic Allan variance (DAVAR) is proposed. The theory of DAVAR is introduced in detail and applied in the study of stochastic errors in dithered RLG. The result shows that the analysis method of DAVAR can not only refine and identify RLG′s stochastic error terms, while confirming the ratio of each error term to the overall error, but also analyze the stability of RLG′s stochastic errors. Compared with Allan variance, DAVAR can represent the characterization of stochastic errors in RLG more completely.