Abstract: Analyzing the masking false failure sets for a given fault is very difficult.A method of identifying the masking false failure sets and computing their conflicting sets is proposed;finding the minimal hitting sets algorithm based on DPSO is applied in enumerating the masking false failure sets;and compared the effect of DPSO with inertial weights because of its characteristic of getting into local optimization.The example in the paper shows: DPSO with linearly decreasing weight not only improves the efficiency but also avoids the phenomena "computation explosion" in contrasting to other similar algorithms,which is adapted to identify masking faults in large-scale compicated systems.