The invention relates to an auxiliary clamping device of pediatric thermometer. The device comprises a main frame, two fixing devices arranged on the main frame and used for fixing the main frame on the shoulders of a human body, a clamping device used for clamping the thermometer, and a clamping fixing frame arranged on the main frame and used for fixing the clamping device and driving the fixedclamping device to enable the thermometer to move to the armpits of the human body. Compared with the prior art, the device has the advantages that the fixing devices are arranged, and the distance between top plates can be adjusted by rotating a rotating wheel, so that the top plates are fixed to the shoulders of a patient and falling is avoided; and the thermometer can be fixed by arranging theclamping device, so that the loss and the breakage of the thermometer can be avoided.