Abstract: Although there is a mass of uncertain information in process of thread assessment, plan recognition quick is very important. A new method for plan recognition based on rough set was put forward. First the model for plan recognition based multi-attribute of rough set was build and calculating methods were given, then concrete examples were demonstrated to test the validity and correctness of the models. The results of the experiment show that the model can promote the efficiency of thread assessment, and give a new technique of pattern matching quick.

Key words: Thread assessment, Plan recognition, Rough set, Value reduct