Abstract: To address the issue of nuclear accident’s consequence assessment and source terms inversion which is of common concern at home and abroad, hybrid genetic algorithm combined puff model was used to back-calculate the source terms including the release rate and the location. The results of comparing the genetic algorithm-Nelder Mead (GA-NM) method with the genetic algorithm-pattern search (GA-PS) method, genetic algorithm (GA) method and Nelder Mead (NM) method show that GA-NM method not only combines the advantages of GA method and NM method, but also compensates the shortcomings of the two algorithms.The inverse value can be exactly match the expected one. Dispersion model module, GA module and NM module can be combined straightforward, and the code used to combine them is very simple, so GA-NM method has a wide versatility. As the calculation of GA module and NM module is less costly, GA-NM method can be used for rapid estimation of the nuclear power plant source terms.