Abstract: Aiming at the problems of various kinds of inconsistency in the collaborative editing,this paper proposed a concurrency control algorithm named ICOT(Improved Context-based Operation Transformation) based on operational transformation.This algorithm is improved on the basis of the COT algorithm and it can reduce the number of operator’stransformation. It solves the problem of the repeating operation transformation by reasonable version of operation in the middle of the transformation.At the same time,this paper gave a concrete example analysis to verify the correctness and effectiveness of the improved algorithm.The results illustrate ICOT algorithm can make copy editor get effective consistency maintenance.

Key words: Concurrent control,Collaborative editing,Transformation of a sequence,Operational transformation,Context of operation,Consistency maintenance