The invention provides a trap-typed capacitor fixing device, consisting of an electrolytic capacitor, an upper capacitor fixing plate, a lower capacitor fixing plate and a fixing support frame. The fixing support frame is arranged at the left and right ends of the upper capacitor fixing plate and the lower capacitor fixing plate. The fixing support frame takes the shape of 'I' and is fixed by bolts. Six to twelve grooves are processed on the internal surface of the upper capacitor fixing plate and are distributed in two rows at intervals. Two layers of counterbores are processed on the lower capacitor fixing plate at the positions corresponding to the grooves of the upper capacitor fixing plate. The terminal of the electrolytic capacitor faces the counterbores of the lower capacitor fixing plate while the other end stretches into the grooves of the upper capacitor fixing plate. The device fastens the capacitor module and facilitates modularized mounting and demounting. The device has excellent insulativity. The device adopts an integral design, wherein, fixing, mounting and wiring of the capacitor are integrated. The device is applicable for the fields of rail vehicle, light rail,subway, Maglev train, industrial converter, etc.