The Allan Variance is usually utilized to analyze gyroscope random error.However, when Allan Variance is used, there is a disadvantage that the estimation vibrates greatly in condition of long correlation time.The traditional Total Variance can solve the problem of Allan Variance, but the problem of excessive calculation exists in Total Variance.To deal with this problem, three kinds of sampling methods are introduced in this paper.In addition, an analysis is made to Allan Variance and Total Variance,based on which the Improved Total Variance is proposed, and an analysis is carried out on MEMS gyroscope random error.The analysis result shows that, the accuracy of Not Fully Overlapping Total Variance is nearly the same as that of the Total Variance, but computational time of the former is not more than 1/1000 of the latters, which can greatly improve the data processing efficiency.