An image tampering forensics method includes labeling an observation clue of a to-be-detected image, constructing a three-dimensional morphable model of an object of a category to which the target object belongs, estimating a three-dimensional normal vector to the supporting plane according to the observation clue, estimating a three-dimensional attitude of the target object according to the observation clue and the three-dimensional morphable model to obtain a plane normal vector to a plane where a side of target object in contact with the supporting plane is located, computing a parallelism between the target object and the supporting plane, and/or among a plurality of target objects, and judging whether the to-be-detected image is a tampered image or not according to the parallelism.