The invention discloses a sensor installing detecting method of a high-precision displacement measuring system. The method includes the following steps that A, at least two times of displacement measurement are carried out respectively, and the measured value alpha ij of each displacement sensor is obtained, wherein i represents the number of times of the measured value, i is a natural number larger than 1, and j represents the number of the sensor; B, aiming at each displacement sensor, an equation is established through the measured value alpha ij of each time corresponding to angular deviation kj and vertical deviation cj; C, any one of the displacement sensors serves as a reference point, and angular deviation ratios and vertical deviation of the other displacement sensors are calculated; D, the installing situation is judged according to the vertical deviation and the angular deviation ratios. The method and the detecting process are simple, the requirement on the testing environment is low, and inspection efficiency is high.