Internal income rate method and net present value method is the assumption that the same item and the cash inflow in the same period will have a different earning ratio of re-investment， this kind of impractical assumption causes fault according to the qualification policy-making. Meanwhile， in the project analysis that needs multi-period investment outlay， the internal income rate method under present computational methods cannot reflect the real earning ratio of the item. Selecting the best strategy by integrating the discount rate of dividing line with the earning ratio of re-investment， analyzing the feasibility by replacing the internal income rate method with the stabilize return ratio， both can increase the validity of strategy.