Provided are a method and an apparatus for detecting pixel defect of optical module, and a device, where the method includes: graying an image obtained by imaging a test binary image by an optical module in a darkroom environment to obtain a first grayscale image; determining a first grayscale area and a second grayscale area corresponding to two gray levels in the test binary image from the first grayscale image; determining a pixel point not matching a grayscale feature of respective grayscale region from the first grayscale area and the second grayscale area respectively as a pixel defect point; and determining the pixel defect of the optical module according to the pixel defect point. The technical solution provided in the present disclosure can detect accurately a pixel defect of an optical module which is advantageous in optimizing the processing technology of the optical module.