The invention relates to a measuring tool and method for measuring the outer contour position and deformation of a transformer. The measuring tool for measuring the outer contour position and deformation of the transformer comprises a base, a height measuring bar, a vertical sliding scale, a horizontal scale, a horizontal sliding scale and a longitudinal height scale, wherein the vertical slidingscale sleeves the height measuring bar and can move up and down along the height measuring bar; the horizontal scale is installed on the height measuring bar by the vertical sliding scale, and the horizontal scale and the height measuring bar are perpendicular to each other; and the horizontal scale is provided with the horizontal sliding scale, the longitudinal height scale is installed on the horizontal scale through the horizontal sliding scale, and the horizontal scale and the longitudinal height scale are perpendicular to each other. By moving the vertical sliding scale and the horizontalscale, the side edge distance of the transformer can be measured, and the specific height and overall height of the transformer can be measured. The high measurement precision is achieved, the determination of a multi-dimensional contour baseline can be realized, distance measurement requirements of corresponding measuring points are met, and the measurement of transformer deformation data can befurther realized.