Main achievements: 1. It’s the first time to adopt GPS real-time differential positioning system to track the direction of buoy, which was successful; 2. Adopted bedrock tested pile to bury the benchmark, which solve the problem of sinking benchmark during periodic engineering of the bridge; 3. Built forced centering observation device to improve the measurement precision of control net and precision of sampling; and 4. Selected different cross-river benchmark measurements to transmit the height of two banks and ensure the accuracy and reliability of cross-river benchmark.