Traditional pulse infrared thermography uses a single pulse with high energy to heat the specimen. For deeper or smaller defects, more energy must be conducted into the specimen to improve the detectability, which also may cause thermal impact damage in particular for composites. Consequently, multi-pulse heating was presented in this study to solve the problem. The multi-pulse is based on heating the materials with two or more pulses separated by a proper time. In this way, more energy can be conducted into the object as well as every pulse thermal impact was separated. Simulation results show that multi-pulse method can not only enhance the defect detectability several times but also is effective to avoid thermal impact damage by restraining the maximum temperature. Ultimately, the optimum separation time for multi-pulse was chosen according to the best inspecting time of single pulse which was estimated by a very simple method.