Disclosed in the present invention is a monitoring apparatus of crane hoisting vertical deviation angle. The monitoring apparatus uses a dual-axis inclinometer to measure the vertical deviation angle of the lifting pulley block of a crane, wirelessly transmits the angle signal, and dynamically displays the angle by a control display. The control method adopts the monitoring apparatus mentioned above. The monitoring apparatus thereof fixes a measuring platform on the outside of the guard plate of the movable pulley of the lifting pulley block, and the dual-axis inclinometer is fixed on the measuring platform surface, which becomes a horizontal plane when the crane hoisting vertical deviation angle is 0 degree. The present invention can detect and monitor the verticality of the lifting pulley block in real time, and avoid the risk of non-vertical crane hoisting.