The utility model belongs to the field of masonry constructional column construction. The utility model relates to a corner cutter, in particular to an adjustable building block corner cutter. Rectangular base, a plurality of fence stand columns are vertically connected to two adjacent frames of the base respectively. Wherein an intersection point of two adjacent edges is a circle center O, two corresponding adjacent frames respectively form an x coordinate and a y coordinate, the fence upright posts closest to the circle center O on the x coordinate and the y coordinate are respectively second limiting upright posts, and a vertical plane formed by the first limiting upright posts, the second limiting upright posts and the first limiting upright posts is a corner cutting surface of the building block. The second limiting stand column and the first limiting stand column are used for forming the corner cutting face and the graduated scale to conduct accurate corner cutting, the secondarystructure brickwork appearance effect can be effectively achieved, the compactness degree of the concrete constructional column is improved, and therefore the construction quality is improved.