The invention discloses an injection process for a metalized polypropylene film dielectric capacitor .The injection process includes the following steps that an injection head for an epoxy resin filling adhesive is closely attached to the inner wall of a capacitor shell, the epoxy resin filling adhesive flows downwards along the inner wall of the capacitor shell, the level of the epoxy resin filling adhesive rises gradually, the position of the injection head shifts upwards constantly, and finally injection is completed .An injection tube serves as the injection head, and the outer wall of the injection tube is defined by an arc outer wall and a planar outer wall .The epoxy resin filling adhesive is prepared from, by weight, 45-60 parts of epoxy resin, 10-18 parts of polyester resin, 5-10 parts of a fire retardant, 30-45 parts of a filling material, 30-45 parts of a diluent, 0.5-1.5 parts of a defoaming agent, 22-35 parts of a curing agent and 0-1.5 parts of a curing accelerator .The epoxy resin filling adhesive is uniformly injected without bubbles inside, the injection process is simple, and the injection efficiency is high.