The invention discloses an automatic feeding device and feeding method used for testing samples at low temperature. Testing accuracy and testing reliability at low temperature are improved, working efficiency is improved, and human power is saved. The automatic feeding device used for testing the samples at low temperature comprises a machine base, a numerical digit impacting testing machine is arranged on one side of the machine base, a lower temperature box is arranged on the other side of the machine base, a conveying mechanism is arranged between the low temperature box and the numerical digit impacting testing machine, the two ends of the conveying mechanism are respectively provided with a support seat, a connecting rod is arranged between the two support seats, and a sliding seat is arranged on the connecting rod. According to the automatic feeding device and feeding method used for testing the samples at low temperature, the time of the exposure of the testing samples at normal temperature is shortened, and therefore the testing samples can be accurately installed on the impacting testing machine.