Automatic liquid extraction system and method and analyzer

The invention provides an automatic liquid extraction system and method and an analyzer. The system comprises a diaphragm pump, a first container and a second container which are communicated in sequence, and the diaphragm pump is connected with a control circuit; a pressure sensor is arranged at a liquid outlet pipe of the diaphragm pump; the control circuit controls the diaphragm pump to extract liquid from the liquid source to the first container, and the liquid is conveyed to the second container through the first container; and the pressure sensor detects the pressure of a liquid outlet of the liquid outlet pipe, when the pressure of the liquid outlet is not smaller than a preset pressure threshold value, the diaphragm pump is controlled to disconnect the internal switch and stop extracting the liquid from the liquid source till the pressure of the liquid outlet is smaller than the preset pressure threshold value, the diaphragm pump is controlled to close the internal switch, and the liquid is continuous