Bandwidth of adaptive optics (AO) system based on stochastic parallel gradient descent (SPGD) algorithm is analyzed theoretically and experimentally. The relation between convergence speed and control channel number of AO system based on SPGD algorithm is researched. Then the bandwidth of AO system based on SPGD is analyzed theoretically by comparson with the traditional AO system with the Hartmann-Shack (H-S) wavefront sensor. A dynamical wavefront distortion correction experiment is performed, and the experimental results verify the theoretical analysis results well. This research can provide a basis for the design and use of AO system based on SPGD algorithm.