The invention relates to an automatic calibration system for urea metering jet pumps, and the system comprises an urea tank, a metering jet pump, a weighing device, a container, a jet pipeline, a reversing valve, a return pipeline and a control module, wherein the container is arranged on the weighing device, and the jet pipeline is arranged at the downstream of the metering jet pump; the urea tank, the metering jet pump and the container are sequentially communicated through pipelines, the reversing valve is arranged at the downstream of the metering jet pump, the jet pipeline is communicated with the reversing valve and the container, and the return pipeline is communicated with the reversing valve and the urea tank; and the control module is electrically connected with the reversing valve, and controls the reversing action of the reversing valve. The invention also relates to a calibration method of the automatic calibration system for the urea metering jet pumps. The system disclosed by the invention is simple in structure and convenient in automatic control operation, and does not cause human errors, thereby greatly improving the calibration efficiency and the calibration precision.