The invention discloses a packing machine for chemical fertilizer manufacturing. The packing machine comprises a first hopper, a first material frame, a conveying device, a circuit control board and an indicator, the first hopper is fixed above the first material frame, the conveying device is fixed below the first material frame, a first discharging port is arranged at the bottom of the first hopper and positioned above a conveying belt of the conveying device, the conveying belt conveys a plurality of packing bags uniformly distributed along the extension direction of the conveying belt, one of the packing bags is positioned below the first discharging port, the conveying belt is provided with a plurality of pressure sensors uniformly distributed along the extension direction of the conveying belt, each packing bag correspondingly presses on one pressure sensor, and the circuit control board receives piezoelectric signals from the pressure sensors, and starts the indicator and drives the conveying device to transmit the next packing bag to be below the first discharging port when the piezoelectric signals reach a preset signal.