The utility model provides a can improve cable shaft construction work efficiency, reinforcing overall structure intensity prevents the modular cable shaft switch board base that switch board slope, the turnover circumstances take place, including square bottom plate, is equipped with square frame form slot at the square bottom plate top surface, set up four blocks of boxboards and enclose the squarely box in square frame form slot, and be equipped with the through wires hole on boxboard wherein the four corners punishment of square frame form slot do not sets up the right angle mount, and be equipped with the card slot respectively on the opposite face of two adjacent right angle mounts, in the slot that the cartridge corresponds on the right angle mount respectively of boxboard both sides, it has the switch board of two make -ups base to enclose at four boxboard tops, and be equipped with the spout respectively at each right angle mount top outer surface, two switch board bases are inserted respectively in the spout that right angle mount surface corresponds, it do not is equipped with the locking plate to lie in the punishment of butt joint face on two switch board base lateral walls, be equipped with connecting bolt respectively at two electric cabinet roof faces.