Abstract: Aiming at the current status that the existing circularly polarized microstrip antenna has defects such as narrow effective bandwidth and large size, a wideband circularly polarized microstrip antenna for 2.4 GHz wireless sensor network is designed. The model of the antenna is established by Ansoft HFSS, and the main structural parameters of the antenna are simulated and analyzed. Finally, the optimal structural parameters of the antenna are derived. Under the optimal structural parameters, the simulation results show that the -10 dB impedance bandwidth of the antenna reaches 63.5%, the 3 dB axial ratio bandwidth reaches 17.5%. At the same time, a vector network analyzer is also used to test the return loss of the antenna, and the test results were consistent with the simulation results. Finally, the designed antenna is loaded onto the CY2420 communication node for communication performance test. The test results show that the average packet loss rate at 150 m of the node is 0.36%, and it is almost the same in any direction. The test results show that the antenna has good circular polarization characteristics and is practical.