Background Cancer is a genetic disease caused by the accumulation of gene mutations. It is important to derive the number of driver mutations that are needed for the development of human breast cancer, which may provide insights into the tumor diagnosis and therapy. Objective This work is designed to investigate whether there is any difference for the mutation mechanism of breast cancer between the patients in the USA and those in China. We study the mechanisms of breast cancer development in China, and then compare these mechanisms with those in the USA. Methods This work designed a multistage model including both gene mutation and clonal expansion of intermediate cells to fit the dataset of breast cancer in China from 2004 to 2009. Results Our simulation results show that the maximum number of driver mutations for breast epithelium stem cells of females in China is 13 which is less than the 14 driver mutations of females in the USA. In addition, the two-hit model is the optimal one for the tumorigenesis of females in China, which is also different from the three-hit model that was predicted as the optimal model for the tumorigenesis of females in the USA. Conclusion The differences of the mutation mechanisms between China and the USA reflect a variety of lifestyle, genetic influences, environmental exposure, and the availability of mammography screening.