The invention relates to the field of engineering machinery and particularly relates to a lifting appliance anti-swaying device of a rotary crane and a control method of the anti-swaying device. An anti-swaying control module is additionally arranged on the basis of a control system of the rotary crane; a light band sensor capable of continuously measuring the coordinate of a lifting appliance in a light plane in real time, a rotary mechanism photoelectric encoder for detecting the rotating speed of a rotary mechanism, a pitching mechanism photoelectric encoder for detecting the pitching speed of a pitching mechanism and a jib approaching switch and a jib position switch for detecting the specific operation height of a jib are simultaneously adopted; the spatial coordinate of a steel wire rope connected with the lifting appliance in the light plane during swaying is measured in real time through the light band sensor and then coordinate information is transmitted to the anti-swaying control module of the control system for analysis and comparison; by changing parameters of a frequency converter to control the speed, the swaying angle of the lifting appliance can be reduced to the range of a set value; the problem that the lifting appliance sways at a large amplitude during the operation of the rotary crane is solved and stable and reliable operation of the lifting appliance is guaranteed.