An ultranarrow-bandwidth-optical-receiver-based ultraviolet trifrequency Rayleigh Doppler wind lidar (DWL) technology is proposed that is able to simultaneously detect stratospheric wind with high precision during the daytime. The lidar system is designed, and the principle of wind measurement is analyzed. An ultranarrow-bandwidth element used for suppressing strong background light is designed as an important part of the ultranarrow-bandwidth optical receiver. A three-channel Fabry-Perot interferometer (FPI) is capable of measuring wind speed. A non-polarized beam splitter cube optically contacted on the three-channel FPI can offer a stable splitting ratio. The parameters of the three-channel FPI are optimized. The structure and parameters of the ultranarrow-bandwidth element are designed, and the transmission curve is measured. The transmission curve and stability of the three-channel FPI are validated. The background photon number is collected with the ultranarrow-bandwidth element and with an interference filter (IF) alternately from 08:00 to 18:00. Based on the selected system parameters and measured background photon number, the detection performance of the proposed lidar is simulated. Simulation results show that with 200 m range resolution from 15 to 25 km, 500 m range resolution from 25 to 40 km, and 30 min total accumulation time for paired line-of-sight (LOS) measurement, within $\pm {100}\;{\rm m/s}$±100m/s LOS wind speed range, the daytime LOS wind speed error is below 4.77 m/s from 15 to 40 km altitude. Compared with the traditional IF-based dual-FPI Rayleigh Doppler lidar, the wind speed accuracies are improved by 1.29-16.29 times and the detection altitudes are improved from 23.55 to 40 km with the same wind-detecting precision.