Abstract: By calculating variance between seismic traces,the conversion from 3D amplitude data to variance attribute data which requires very long running time can be realizde,so traditional methods cannot satisfy the practical need.In order to shorten the periods of the seismic data interpretation,the authors have improved the algorithm of the traditional variance cube based on the analysis of the algorithm and adopted recursive algorithm to improve the speed.This paper introduced the improved algorithms and developed the software of variance cube technique.By testing,it is fined that the speed of calculating is obviously increased from the practical application which verifies the validity of the algorithms.Using time slice and stratal slice,can interpret small faults and analyze geological structures by analyzing the similarity of seismic signals between adjacent traces on the seismic cube.An analysis and interpretation of practical data show that the variance cube technique is very effective in the identification of small scale faults and fractured zones,therefore,it can improve the seismic interpretation precision.