Aiming at the phased array antenna in the field of aerospace multi-target measurement and control, a dual circularly polarized microstrip phased array sub-array antenna with a size of 116 mm×116 mm×16 mm working in the S-band is designed. The antenna adopts two feeding modes of probe contact and electromagnetic coupling to achieve a wide frequency band; a 90° polarization hybrid is used to achieve simultaneous double circular polarization of left and right rotation. The research results show that the return loss of the sub-array antenna in the working frequency band＜–16.3 dB, the same polarization isolation and the opposite polarization isolation 15 dB, the peak gain can reach 8.3 dB, the half-power beamwidth of the pattern＞35°, and the voltage standing wave ratio 1.43, the axial ratio within the range of ±60° 2.1 dB, the simulation and test results are in good agreement. At the same time, the antenna has the characteristics of low profile (height dimension is 0.1 λ0, λ0 is air medium wavelength), simple structure, easy processing, etc., meeting the expected design requirements. It provides technical basis and product support for the company''s multi-objective phased array measurement and control system development.