Abstract: In order to solve the problem of positioning and lofting accuracy in the assembly of large-size serpentine tube screen, a set of laser automatic lofting system was developed. System design involves the optimization of the software framework structure and the efficient integration of the control system. In addition, a high-precision calibration technique for multi-laser projection subsystems is introduced. Through field experiments, the system has demonstrated excellent operational feasibility. The final experimental results show that the laser automatic lofting system developed in this paper can reach 0.13mm in the range of 15m, which can well meet the application requirements of the production site.