The invention discloses a method for accurately controlling photographic density during radiographic inspection. The method includes 1), placing films and a radial dosimeter under each step of step test blocks, and clearing accumulated data of the radial dosimeter to zero; 2), exposing; 3), washing and airing the exposed films to obtain negative films, measuring optical density of the negative films through the radial dosimeter and reading corresponding accumulated doses; 4), reading accumulated doses AH and AL respectively corresponding to an upper-limit black matrix and a lower-limit black matrix required by technological detecting regulations from the negative films, and setting an alarm threshold value of the radial dosimeter into a dose value corresponding to a suitable optical density or other values in range of [AL,AH] as required; and 5), transilluminating and exposing to-be-detected workpieces, stopping exposing immediately when the radial dosimeter sends alarms, and keeping the optical density of the negative films in a value range required by the regulations. The accumulated doses of the radial dosimeter are adopted to control exposure time so as to control the optical density of the films, so that exposure curves are not needed to produce too much, time and energy are saved, and problems of fixing transilluminating focal distance, fixing tube voltage and the like are not needed to be considered.