This work investigates the joint beamforming and power allocation scheme of terrestrial-satellite network in high-speed railway scenario, where, base stations (BS) and satellite work together to provide universally available communication service for ground users. Firstly, based on the historical travel information of high-speed railway, such as deterministic direction, known speed, and predictable trajectory, we propose a phase-based beamforming design to compensate for the Doppler effect and improve the system total capacity performance. Combing the phase-based beamforming design with the BS’s maximum ratio transmission (MRT) beamforming and the satellite’s zero forcing beamforming (ZFBF). Secondly, considering the performance of the satellite, we maximize the overall system capacity, ensuring compliance with the satellite's baseline capacity requirements. Then Lagrange sub-gradient joint power allocation algorithm is derived to improve the users’ signal-to-noise ratio (SNR) and maximize the total system capacity. Finally, the effectiveness of the proposed algorithm is assessed through simulation-based validation. The simulation outcomes substantiate that, in comparison to the greedy algorithm, the power allocation strategy introduced in this study enhances the system capacity by approximately 25% .