The invention discloses a flexible control method for action starting and stopping of an upper-air work platform car cantilever crane. PWM signals are output through logic control in a controller to control a proportional valve, and the PWM signals of the proportional valve are cantilever crane action control output signals. The flexible control method is characterized in that starting and stopping control is divided into a slope starting control method and a slope stopping control method; and Yout output of the PWM signals of the proportional valve under different control methods is achieved through the logic relation among Xmin, Xmax, Ymin, Ymax, Xin, Active, AAC, ADC and Yauto. According to the flexible control method for starting and stopping, the limitation that operation stability of a traditional work platform depends on the skills of operators is broken, and operation safety and comfort are improved; and a quadratic function curve starting and index function curve stopping mode is adopted, action starting and stopping can be more stable through the mode, and no signal mutation phenomenon exists.