The fast multipole method (FMM) is a fast and efficient numerical algorithm for solving the Nbody problem and has various applications in cosmology and molecular dynamics. Sunway SW26010 is a heterogeneous manycore processor developed independently by China with 260 cores (4 core groups). We design and implement an FMM  on SW26010 manycore architecture. We also systematically optimize the performance  of kernel functions (especially for the most timeconsuming particle pair interaction), including asynchronous direct memory access (DMA), SIMD vectorization, loop unrolling and inline assembly tuning. Taking the particle pair interaction kernel as an example, the computational speed after optimization is about 400 times higher than the raw code running on the host core, and the floating-point performance on each core group is 250 GFLOPS, which is 32.5% of the theoretical peak performance.