Abstract:Based on the fitting of GPS height measurement with two engineering examples, this paper analyzes how to achieve the third, fourth class leveling’s requirements. We compare the evations obtained from the GPS height fitting and conventional level, statistically analyzed the precisions of GPS/level observation elevation fitting, analyzed the influence of GPS observation grade to the precisions of GPS/level observation height fitting,assess the level’s grade of GPS elevation fitting by using the conventional level tolerance,and anazlyzed the practicability of GPS elevation fitting. The results show that: the GPS height fitting measurement can replace the leveling measurement under certain conditions.