Abstract: In this paper, the fault tree of line displacement sensor is established for the abnormal output fault of the actuator line displacement sensor. It is determined that the fault is caused by the undefined bending allowance of the enameled wire between the two fixed tape ends of the line displacement sensor, and there is assembly pre-tightening force existing in the fixing process, under the combined action of the assembly pre-tightening force and the temperature environment stress, irreversible damage is caused to the material, which eventually leads to the breakage of the enameled wire. Measures such as eliminating the pre-tightening force of enameled wire assembly between tapes, increasing the temperature screening test are adopted, which are proved to be effective. The analysis shows that the quality of linear displacement sensor is closely related to the process control, and the process should be strictly controlled to ensure the stability of product quality.