The utility model discloses a negative pressure structure for an SD (
Sprague Dawley) rat milk electric collecting device, which belongs to the field of electric breast pumps and comprises an electric collecting device shell and a negative pressure component arranged in the electric collecting device shell. The negative pressure
assembly comprises a
piston mechanism and an electric push rod connected with a shaft rod of the
piston mechanism. An adjusting
assembly is arranged in the electric collecting device shell; the adjusting
assembly comprises a sensor connected with a shaft rod of the
piston mechanism, magnetic elements in
signal connection with the sensor are arranged on the two sides of the sensor, and a driving lead screw is inserted into one magnetic element in a threaded mode. According to the negative pressure mechanism, through the arranged adjusting assembly, the moving distance of the
piston rod in the piston
barrel is adjusted and controlled, the size of a cavity for forming negative pressure in the piston
barrel is conveniently adjusted, then the
suction force of the negative pressure structure can be adjusted, and the device can be adjusted according to the
suction force needed by different SD rat nipples; the collection efficiency is improved, and the applicability of the device is improved.