Soliton optical combs in microresonators have broad application prospects in coherent optical communication, optical frequency synthesis, lidar, microwave photonics and quantum optics. Efficient prism coupling provides an inevitable technical approach for integrated application and system packaging of soliton frequency combs in crystal microresonators. In this paper, a MgF2 microresonator-prism coupling system with the coupling efficiency of 71.56% and loaded Q value of 1.8×109 was developed. Based on this efficient prism coupling system, the generation of MgF2 microresonator soliton frequency comb and the low-phase noise microwave signal of 15.99 GHz were realized. And the phase noise level of beat frequency signal is about -117 dB/Hz@10 kHz. It will promote the practical application and development of low-phase noise micro-photoelectric oscillator.