The application discloses a hydraulic mechanism of a tubular busbar precamber machine, comprising a precamber mold, a hydraulic press, an oil pump and an oil pump motor; wherein the hydraulic press comprises a pedestal and a telescopic arm, the pedestal is fixed in a hanging box body of the tubular busbar precamber machine, and the telescopic arm is arranged on the pedestal; the precamber mold is fixed at the top end of the telescopic arm of the hydraulic press, and the upper surface of the precamber mold is an arc-shaped surface; the oil pump is communicated with the hydraulic press, and the oil pump motor is electrically connected with the oil pump. Compared with the conventional handmade precamber, the hydraulic mechanism provided by the embodiment of the application controls the precamber force of the precamber machine just by the oil pump motor, so that the precamber time-consumption is smaller, the operation is simple, and the percamber efficiency is higher.