In order to better control the measurement accuracy of the steel structure of the FAST cable mesh, it can be controlled by measuring the welded ear plate on the steel structure. The ear plate is used to connect 150 edge main cables of the FAST cable network, and is uniformly welded on the ring steel structure with a diameter of 500m, so the accuracy of the measurement ear plate can reflect the measurement accuracy of the steel structure. Now by using the virtual point measurement method for measurement, that is, the basic principle of symmetric measurement error analysis, determine the main source of measurement error, and formulate corresponding quality control measures during the measurement process, to ensure that the ear plate measurement meets the measurement accuracy requirements of FAST engineering.