The invention discloses a method for acquiring a characteristic size of a remote video monitored target on the basis of a depth fingerprint, which comprises the following steps of: acquiring a plurality of slice images of a region of interest of a monitored scene of a target video monitoring system by a gated imaging technique, overlapping the slice images to obtain a depth fingerprint of the region of interest and implanting the depth fingerprint into the target video monitoring system; when the monitored target appears in the region of interest, extracting the monitored target from the background, matching the monitored target with the depth fingerprint, and determining fingerprint lines which are subordinate to foot characteristic lines of the monitored target, wherein space distance information of the fingerprint lines is target distance information; and after acquiring the target distance information, inverting information of the characteristic size of the target from the length of a characteristic segment of the target to be measured, which takes a pixel as the unit, in a monitoring image according to a mopping relation between a three-dimensional space and a two-dimensionalimage plane under the condition of a perspective projection model. By the method, the problem that a conventional remote video monitoring system is difficult to acquire the information of the characteristic size of the target is solved.