Abstract: In order to meet the demand for rapid monitoring of bolt preload force in major engineering fields, this thesis derives the preload force measurement equation by longitudinal wave method according to the acoustoelasticity principle and Hooke's law, and builds a 1.25 GHz high-sampling ultrasonic bolt preload force measurement system. The frequency domain time-delay estimation algorithm is proposed by combining the frequency domain upsampling principle and the frequency domain interpolation time-delay estimation algorithm; the stability of the calculation results of the interpolation time-delay algorithm is verified by using simulation, and the stress coefficient of 1.680 MPa ·ns^-1 is determined by the calibration test for the selected grade 8.8 M30 carbon steel bolt. then the loading test is conducted for this type of bolt test result show that the frequency domain interpolation time-delay algorithm accuracy can reach 3.5%, the operation speed is about 5 times higher than the traditional time domain interpolation algorithm.