The invention proposes a plum round contact-adjustable connection device of a handcart-type vacuum circuit breaker. The plum round contact-adjustable connection device comprises a spring ratchet wheelclamping connection head, clamping handles, an assistant spring and a trip device, wherein the spring ratchet wheel clamping connection head is arranged at front ends of the two clamping handle connected by a rotation shaft, wiring terminals are arranged at outer sides of the clamping handles and are used for connection test lines, the assistant spring is connected with inner sides of the two clamping handles, the spring ratchet wheel clamping connection head is hermetically connected with a plum round contact by the assistant spring and the trip device, the trip device comprises a rack, a ratchet wheel, a paw and a stretching spring, the rack is connected between tail parts of the two clamping handles, the ratchet wheel is arranged on the clamping handle and is engaged with the rack, thepaw is arranged at an outer side of the ratchet wheel and is limited and fixed by the stretching spring, and one end of the clamping handle is fixedly connected with an adjustable insulation plate. The trip device is employed, the spring ratchet wheel clamping connection head contracts at the plum round contact for separation, and the connection device is firm, safe and reliable to connect and issuitably used as a handcart-type vacuum circuit breaker connection device.