The sealing reliability of through-cabin optical fiber connector is curcial for maintaining the stability of air pressure in manned spacecraft cabin and ensuring the safety of manned spacecraft. In order to ensure the reliable application of the through-cabin optical fiber connector in the complicated space application environment and long service life in orbit, a high reliable bi-au-tin optical fiber sealing structure of the through-cabin optical fiber connector is proposed, and the mechanism of optical fiber metallization welding seal is analyzed. Based on the requirements of the cabin connection application sealing capacity≤10^-10 （Pa·m³）/s and ambient temperature -100 ℃ to 100 ℃, the structure of a multi-core through-cabin fiber connector with double gold tin fiber sealing structure is analyzed. The sealing reliability of the multi-core through-cabin fiber connector is ensured by structural design such as pressure degradation, temperature buffer and low stress structure. Through solder selection, CTE matching analysis, secondary sealing process validation analysis, and small batch trial production, research on the metallization fiiber optic welding sealing process is performed to validate the rationality and stability of the double-gold tin fiber seal structure design and process technology. The experimental valudation demonstrates that the optical performance and sealing leakage rate of the multi-core optical fiber connector are qualified after the extreme space environment tests such as temperature shock, rapid pressure drop and high strength sinusoidal vibration. This confirms that the optical fiber connector using double gold tin optical fiber sealing technology can meet the long-term requirements of manned spacecraft in orbit and has good reliability.