Abstract: In order to solve the problem of classical rough sets theory in processing mixed decision table’s discretization with too many rules and low accuracy，the discretization method based on the greedy algorithm and the attribute value sector probability is used，it changes the traditional method of only process continue attributes for mixed decision table.Firstly，this method only discretizes continue attributes for mixed decision table with the improved greedy algorithm，then computes continual attributes interval probability，and subdivides the sector with the maximum probability，finally considers further discretization for the original discrete attributes.The experimental simulation result indicates this method can strengthen the resolution，reduce the rule number，and always accommodate decision table after discretization，many present separate methods which doesn’t consider the policy-making compatibility，it can retain the system useful information.It shows the validity and veracity of the method.