Aiming at the problem that existing signal bandwidth estimation algorithms are not conducive to engineering implementation or have a low estimation accuracy, a new estimation method based on geometric analysis of power spectrum distribution function is proposed. Firstly, the average power spectrum of the signal and its distribution function are calculated. Then, the geometric triangle thought is used to estimate the bandwidth in the distribution function graph. Finally, the linear gradient approach is used to revise the estimation result, and the bandwidth estimation of the satellite communication is effectively implemented. Simulation results show that the normalized root mean square error is less than 10^-2when the signal-to-noise ratio is 0 dB, and the method is simple and easy to implement.