The invention belongs to the technical field of shoemaking production, and particularly relates to a rapid forming production method of a custom insole. The rapid forming production method adopts an outer box body; a foot model acquisition unit is arranged in the outer box body, and a leg supporting device is arranged at the end part of the outer box body; an elastic silica gel layer arranged on the foot model acquisition unit is concave downwards under the action of a pushing force of sizing pillars which are uniformly and densely arranged so as to form a foot model shape similar with a footshape of stepping personnel, after the foot model shape is formed in a sizing box, an operator pours molten insole solution into the sizing box by a pouring basin, and the poured solution primarily forms the custom insole between the elastic silica gel layer and a foot model forming plate, so that different sizes and types of insoles can be customized according to requirements of personnel who customize the insoles; and according to a supporting force of a regulation supporting seat of the foot supporting device for personnel, stepping forces of stepping personnel on a foot model sizing plateare different, so that a lateral surface coated insole which needs to be customized can be customized for customizing personnel.