The invention provides a method for making a square box and relates to paper box making methods. A piece of square paper is gotten, and two transverse indicative lines and two longitudinal indicative lines are made; first paper corner triangles, second paper corner triangles and isosceles trapezoids are folded, and the square paper becomes a longitudinal rectangle; the longitudinal rectangle is turned over by 180 degrees to form a turned longitudinal rectangle, oblique line positive broken lines are made, folding is conducted, and the turned longitudinal rectangle becomes a hexagon composed of an upper right trapezoid and a lower right trapezoid which share the same lower bottom; folding and attaching are conducted according to overlapping transverse positive broken lines, short positive broken lines, short negative broken lines and intersection positive broken lines, and meanwhile folded portions are folded into interlayer openings, so that a double-trapezoid hexagon composed of two isosceles trapezoids sharing the same lower bottom is formed; the surface layer is propped open from inside to outside at the lower bottom of the trapezoids of the double-trapezoid hexagon, 90-degree folding is conducted according to connecting line negative broken lines, the lateral sides of the isosceles trapezoids are unfolded into planes accordingly, and therefore the square box is obtained. The square box is novel in design, easy to make, simple in model, firm, stiff, attractive in appearance, and practical.