Abstract: The present invention discloses a support mechanism of a self-adaptive traction robot for a complex wellbore and a control method thereof, and relates to the technical field of oil and gas field development. Each support link assembly in a support mechanism is controlled by an independent hydraulic cylinder and hydraulic valve. When a well wall that each support link assembly contacts in a circumferential direction is irregular, the support mechanism contact effect is not ideal, which leads to a decrease in traction force. In this case, a displacement sensor in a telescopic mechanism detects that a displacement of a traction cylinder piston is small, which is fed back to a ground control system, and then a fluid inflow size of support cylinders corresponding to different support link assemblies is adjusted until the displacement sensor in the telescopic mechanism detects an effective traction distance.