An umbrella-shaped deployable reflector antenna with phased array feed is designed to meet the requirements of spaceborne high-gain antenna in this paper. Firstly, the principle and design of the deployable mechanism of reflector antenna are introduced. The reflector consists of carbon-fiber rid and braided metal net, which can be closed and expanded under the action of the high-precision deployable mechanism, thus greatly reducing the size of the collection envelope. A wideband phased array feed is designed for the 1.14-meter aperture deployable reflector antenna, and the metal Vivaldi antenna is used as the element of the phased array. According to the polarization mode, the reflector f/D and scanning range, a rectangular dual-polarized Vivaldi array is arranged and used, realizing a two-dimensional scanning range in the frequency range of 8~16 GHz. Simulation results show that antenna gain at 8 GHz, 12 GHz, 16 GHz is 38.03 dB, 40.65 dB and 41.48 dB scanning to 0°, and 37.68 dB, 40.68 dB and 41.09 dB scanning to +3° respectively, validating the wideband phased array feed can effectively increase the field of view of the deployable reflector antenna.