Traditional design for testability (DFT) is arduous and time-consuming because of the iterative process of testability assessment and design modification. To improve the DFT efficiency, a DFT process based on test point allocation is proposed. In this process, the set of optimal test points will be automatically allocated according to the signal reachability under the constraints of testability criteria. Thus, the iterative DFT process will be completed by computer and the test engineers will be released to concentrate on the system design rather than the repetitive modification process. To perform test point allocation, the dependency matrix of signal to potential test point (SP-matrix) is defined based on multi-signal flow graph. Then, genetic algorithm (GA) is adopted to search for the optimal test point allocation solution based on the SP-matrix. At last, experiment is carried out to evaluate the effectiveness of the algorithm.