Abstract: Aiming at the limitation of dependency model in description and analysis of uncertain problem for testability analysis of complex circuit board, a testability analysis method is put forward based on fault simulation and rough set.Firstly, condition attributes are generated through fault simulation.Then, discernibility matrix is provided by rough set reduction.And moreover, the fault detection rate and fault isolation rate of circuit board can be calculated based on the matrix.Finally, an example proves that our method is feasible and effective.