The invention discloses a pre-positioning device for a capacitor. The pre-positioning device comprises a bracket and an electrode lead-out terminal unit; rectangular stopping jacks passing in the front-rear direction are formed in the middle portions of transverse support plates; a pair of longitudinal support plates are inserted into the stopping jacks of the pair of transverse support plate in the front-rear direction; a plurality of uniformly distributed transverse lower connecting holes passing in the up-down direction are formed in the transverse support plates; a plurality of uniformly distributed longitudinal lower connecting holes passing in the up-down direction are formed in the longitudinal support plates; a plurality of uniformly distributed transverse connecting holes passingin the up-down direction are formed in the horizontal portions of the transverse support plates; a plurality of uniformly distributed longitudinal connecting holes passing in the up-down direction areformed in the horizontal portions of the longitudinal support plates; the electrode lead-out terminal unit includes four electrode lead-out terminals and a connecting plate fixed to the lower ends ofthe four electrode lead-out terminals. The pre-positioning device is simple in structure, is suitable for different capacitors and electrode lead-out terminals, and has high the connection quality ofthe electrode lead-out terminals.