Least-squares Monte Carlo method (LSM) is a method for pricing American options. The approach can give accurate option prices but it is computation intensive. In this thesis we use data–parallelism techniques to accelerate LSM with GPUs; that is, we will divide the computation paths into mutually independent groups. As for the least-squares calculation, QR decomposition is employed. The program is implemented by using CUDA to run on GPUs. The numerical results are compared with a sequential program’s on CPUs. The experiment results show that the more groups are created, the less time it takes to execute.