In view of the M_S7.4 Maduo earthquake in Qinghai Province on May 22, 2021, the coseismic strain waves observed by three types of borehole strain gauges are compared and analyzed. the results show that there exist some differences in the initial motion time, fluctuation amplitude and duration recorded by the three instruments. In the case of the same epicentral distance, TJ type bulk strain gauge and RZB type four-component borehole strain gauge are not good of small fluctuation range and short duration, which makes it difficult to distinguish the coseismic response from the background change, affecting the coseismic law of borehole instrument. the YRY-4 four-component borehole strain gauge has a large fluctuation range and a long duration, and has outstanding performance in seismic reflection effect.