Abstract: Calculating the γ radiation dose field in three-dimensional space is of great significance in the optimization of the working path and the design of radiation shielding during the decommissioning of nuclear facilities and the overhaul of nuclear power plants, and is one of the basic tasks to realize the optimization of radiation protection. The point kernel integration method uses a semi-empirical analytical calculation method to calculate the γ radiation dose field in three-dimensional space, which has the advantages of intuitive principle, simple calculation, complete parameters and fast calculation speed. In the point kernel integration method, it is of great significance for the update of the accumulation factor. In this paper, the accumulation factor in the point kernel integration method is studied in depth, and the accumulation factor is updated based on the G-P method, and compared with the results of ANSI/ANS and MCNP5, and the results show that the accumulation factor calculated based on the G-P method is closer to the benchmark results of ANSI/ANS. Subsequently, the accumulation factor calculation module of the QAD-CG program was updated, and the QAD-CG-GP program was developed. The results show that the dose rate calculation results of the QAD-CG-GP program are closer to the benchmark results, indicating that the point kernel integration program can achieve higher calculation accuracy after updating the accumulation factor based on the G-P method.