Telescopic control method, system and telescopic arm structure of single-cylinder plug pin of crane

The invention relates to a telescopic control method, a telescopic control system and a telescopic arm structure of a single-cylinder plug pin of a crane. The telescopic control method of the single-cylinder plug pin of the crane comprises the steps of when a target suspension arm needs to stretch out and draw back, inserting a cylinder pin (4) of a telescopic oil cylinder barrel (3) into a cylinder pin hole of the target suspension arm so as to fix the target suspension arm and the telescopic oil cylinder barrel (3); transferring force applied to an arm pin (6) to the cylinder pin (4), and then retracting the arm pin (6); after the target suspension arm moves to be in place, releasing the arm pin (6) so as to lock the position of the target suspension arm, transferring the force applied to the cylinder pin (4) to the arm pin (6), and retracting the cylinder pin (4) from the cylinder pin hole of the target suspension arm. According to the method, the system and the telescopic arm structure, unlocking of the cylinder pin and the arm pin is easy.