Abstract: In order to solve the problem of low directivity of parallel coupling line microstrip directional coupler in the case of weak coupling, a miniaturized high-directivity microstrip dual directional coupler suitable for high-power occasions is proposed. Based on the traditional quarter-wavelength parallel-coupled three-line microstrip dual directional coupler structure, the size of the coupler can be significantly reduced while the isolation of the coupler can be increased by using microstrip radial stub capacitance, and the directivity can be further improved by introducing sawtooth structure into the coupling edge. The load resistance grounding adopts microstrip radial stub design to avoid electrification via holes, which makes the processing simpler. A microstrip dual directional coupler with a central frequency of 915 MHz and a coupling degree of 20 dB is designed. HFSS simulation software is used to optimize the design, and the prototype is fabricated and measured. The measured results show that the coupling degree at the center frequency is 20.2 dB and the directivity reaches 32.1 dB. In the frequency band of 0.74 GHz to 1.35 GHz, good input matching is obtained while the fluctuation of coupling degree is less than 0.5 dB and the directivity is higher than 20 dB.