Office chair with adjustable back structure

The utility model provides an office chair with an adjustable back structure. The office chair comprises a chair back, a chair seat and a movable seat, the chair back comprises a rubber back frame and a back frame; the top of the rubber back frame and the top of the back frame are fixed through lock screws; a fixing plate is fixedly arranged at the lower end of the back frame; a waist propping rubber sheet is arranged between the rubber back frames, a first rotating part is arranged at the lower end of each rubber back frame, a rotating arm corresponding to the first rotating part is fixedly mounted on the bottom surface of the chair seat to form a first rotating point, and the rubber back frames rotate relative to the chair seat; a chassis is fixedly mounted at the bottom of the chair seat; the chassis comprises a fixed part and a rotating plate; the fixed part is rotatably connected with the rotating plate to form a second rotating point; and the fixed plate is detachably connected with the rotating plate t