The invention belongs to the technical field of optical imaging and detecting and relates to a bilateral dislocation differential confocal measuring method. According to the method, due to the dislocation differential subtracting process on data sets on the two sides of the confocal axial characteristic curve, the position of the extreme point of a confocal system characteristic curve is accurately obtained. Due to the fact that two sections of data, close to the position of the full width at half maximum and very sensitive to axial displacement, of the cofocal characteristic curve are used for conducting the dislocation differential subtracting processing, the position, calculated by the data sections, of the extreme point of the confocal characteristic curve is more sensitive than that the position, calculated through an existing confocal characteristic curve top fitting method, of the extreme point of the confocal characteristic curve, according to the result of the bilateral dislocation differential confocal measuring method, under the condition that the structure of a confocal microscopy system is not changed, the axial resolving power, the signal-to-noise ratio and the like of the existing confocal microscopy system can be obviously improve, and a new technological approach is provided for the field of confocal imaging or detecting.