The optical axis consistency index of an electro-optical device with side hanging structure of a sensor is out of tolerance. Through the analysis of the structure of the optical bench, sensor cover and other related parts of the electro-optical device, the flatness of the mating surface of optical bench, sensor cover and the sensor mounting surface of optical bench was optimized, the accuracy was improved, and the wall thickness was appropriately increased. The modal analysis of the optical bench before and after improvement was emphasized. The improved electro-optical device was verified and tested by building a test device, and the test data were analyzed. The test results show that the improvement measures are effective in improving the optical axis consistency of the electro-optical device.