The water depth of Lufeng 15-1 jacket platform field is about 286m, the jacket is installed using launching from the barge, LF15-1 is the first 300m-series deepwater jacket in China. In the design phase, MOSES time domain launch program is utilized to simulate jacket launching process. In order to verify the accuracy of motion analysis, to ensure the jacket safety during the launch process and to provide support data for the subsequent projects, the jacket launching trajectory monitoring system is installed on the jacket, to monitor the jacket and barge motion during the entire process. All main monitoring parameters are within the design limitations, but there are also some obvious differences in some results, such as jacket top diving depth, barge and jacket pitch angle. In this paper, based on the field observation results, MOSES time domain launch program is utilized to conduct back analysis of launching process, and sensitivity studies are performed for the key differences. The research results could provide reference for future deepwater jacket launching design.