In the process of design and research on simply guided bomb, the measurement of rotating speed is particularly significant. According to the high rotating speed of conventional ammunition, a method of measuring rotating speed based on strap-down single-axis magnetic sensors was presented. The mass point trajectory model and vehicular magnetic field model, as well as the single-axis magnetic sensors model were established. Then the output data of magnetic sensors was simulated by Matlab. The bullet rotating speed data was extracted from the magnetic signal based on Chirp-Z Transform (CZT). Finally, with the error analysis of simulation results, the test results were presented. The experiment results show that the rotating speed measurement method used in the simulation is feasible.