The invention discloses a rubber plug automatic injection device. The device comprises a feeding mechanism, a rubber plug moving mechanism, a rubber plug injection mechanism and a fixed base, the rubber plug moving mechanism comprises a first moving mechanism and a moving part matched with the first moving mechanism, a moving rail penetrating in the thickness direction of the moving rail itself and matched with the rubber plug is formed in the moving part, and the rubber plug injection mechanism comprises a second moving mechanism and an indentation part matched with the second moving mechanism. The rubber plug automatic injection device is capable of automatically conveying and injecting the rubber plug, the operation is simple, the efficiency is high and the effect is more obvious in the situation of the rubber plug in a smaller size.