The invention belongs to the related technical field of heat collecting pipe production, and discloses an automatic pipe breaking device for a vertical heat collecting pipe production line. The automatic pipe breaking device comprises a body, a linear bearing, a spring, a double-roller mechanism, a double-cam mechanism, an auxiliary shaft, a main shaft, a rolling linear guide sleeve pair and a cutter; a containing hole is formed in one end of the body, a sliding bearing block is arranged at the other end of the body, and two supporting blocks are arranged in the middle of the body at intervals; the linear bearing is arranged in the containing hole; the rolling linear guide sleeve pair is arranged on the sliding bearing block; one end of the main shaft penetrates through the linear bearing,and the other end penetrates through the sliding bearing block and then is connected to the cutter; the double-roller mechanism is fixedly connected to the main shaft, the spring is arranged on the mains shaft in a sleeving mode, and the spring is located between the linear bearing and the double-roller mechanism; and the two ends of the auxiliary shaft are arranged on the two supporting blocks respectively, the double-cam mechanism is arranged on the auxiliary shaft, and two cams of the double-cam mechanism are separately connected with two rollers of the double-roller mechanism respectively. According to the automatic pipe breaking device, automation is achieved, and the structure is simple.