Testability is crucial for the enhancement of system maintainability, and testability growth can promote the testability metric of the system to satisfy the design requirements by a series action of identifying and correcting the testability design defects. The test resources allocating problem arising in delay fix based testability growth was studied and modeled, considering that whether there are constrains on the growth object and growth test cost or not. A Lagrangian relaxation algorithm and local search hybrid optimal algorithm were applied to solve this problem. Simulation results show that the proposed model is feasible for the test resources allocating problem in testability growth test, and the hybrid optimal algorithm can promise the effectiveness and accuracy to the integer programming problem.