Anti-collision protective device and method for drilling top drive and derrick racking platform

The invention relates to an anti-collision protective device and method for a drilling top drive and a derrick racking platform. Hang ring position detecting switches are installed at the forerake position and the hypsokinesis position of a top drive hang ring respectively, and a hang ring suspension detecting switch is arranged in the middle suspension position to judge the position state of the top drive hang ring. An encoder is installed on a winch and can output multiple pulse records when a roller on the winch is rotated by a circle; a central control unit indicates the height of the top drive in a derrick according to the pulse number recorded by the encoder, the position of the top drive hang ring and the height of the top drive are processed and compared in the central control unit to achieve collision prevention of the racking platform position. The anti-collision protective device has the advantages that the independent top drive and the winch are systematically and organically combined together, defects of respective designs are overcome, safety of equipment operation is greatly improved, and the situation that the top drive hang ring collides with the racking platform due to human errors and other serious related accidents caused by collision is effectively prevented.