This paper presents a QPSK phase recovery algorithm for coherent inter-satellite optical wireless communication (IsOWC). From theoretical perspective, we explain the process of the multiplier-free algorithm. Through simulations, we analyze key parameters and provide guidances on their optimal selection. Additionally, proposed algorithm maintains stable phase tracking at Eb/N0 as low as 4 dB. In ob2b transmission test, our algorithm achieved a sensitivity of -49 dBm @5 Gbps QPSK (HD-FEC limit). Compared to the V&V algorithm, its receiving sensitivity is improved by 1 dB, resulting in a link distance extension of 1100 km. Our multiplier-free and robust algorithm meets the requirements of IsOWC systems and shows promise for future applications.