[Abstract] In this paper, a miniaturized ultra-wideband antenna array is designed to meet the needs of geological imaging in coal mine. The antenna array is a planar array composed of 7 radiation elements, 3 transmitting and 4 receiving. Each radiation element is composed of two Vivaldi slot line antennas arranged crosswise, which can realize bilinear polarization detection. The antenna design was simulated by HFSS. According to the simulation results, the VSWR was <2 and gain was >3dB every Vivaldi slot. Finally, the antenna was tested in a microwave anechoic chamber, and the test results show that the VSWR and gain performance of the antenna are consistent with the simulation results, which meet the design requirements of geological imaging system.