It adopts counter pressure filling princple. The filling valve adopts high precision mechanical valve. It has advantages of fast filling speed, high precision in liquid level and it only starts filling when there is a can, otherwise it will not fill. Using the device structure of filling valve precover device and supporting bottom device, it can guarantee the maximum stability of cans when they passing in and out of the filling machine. Filling cylinder braces use worm-gear box going up and down to satisfy cans of different height. Float switches in the filing cylinder ensure a smooth liquid inlet.