The magnetic fieldintensity of the probe in the borehole fluid magnetic logging tool varies with the ambient temperature, resulting in a change in the nuclear magnetic resonance frequency. Determining the preferred highvoltage pulse frequency for the transmitting antenna in the operating environment is important for obtaining a high signal to noise ratio of the echo signal and is one of the identified parameters required for fluid NMR logging. Designing and achieving a DSP and FPGA jointly control the DDS chip of the sweep circuit which can complete the frequency of fast and accurate switching and determine the nuclear magnetic resonance frequencies at different temperatures. Experiments show: The circuit emits highvoltage pulse frequency in the range of 4 MHz to 5 MHz and can determine the best highvoltage pulse frequency at different ambient temperatures with frequency accuracy of 10 kHz.