The invention relates to the field of measurement, and especially relates to an image measurement method, system and device. The method comprises the steps: presetting the initial position of a camera, and rotating the camera so as to enable a shooting area to be located in a display area of the camera, and obtaining a rotation angle value of the camera; adjusting the direction of a laser beam emitted by a laser disposed on the camera, enabling a laser point located in the shooting area to be located at the center of the display area of the camera, and capturing a two-dimensional image throughshooting; calculating and obtaining a translation value of the camera according to the distance, obtained by the laser, from the camera to the shooting area; obtaining the preset internal parametersof the camera, calculating and obtaining the mapping relationship between the two-dimensional image of the shooting area and a three-dimensional world space according to the rotation angle value of the camera, the translation value of the camera and the internal parameters of the camera; obtaining the coordinate values of a to-be-tested object on the two-dimensional image, substituting the coordinate values into the mapping relationship between the two-dimensional image and the three-dimensional world space, and calculating and obtaining a measured value of the to-be-tested object in the three-dimensional world space.