The invention relates to a connection structure of a sidecar tricycle main frame and a sidecar frame, wherein the main frame comprises a main frame main pipe (1), a main frame auxiliary pipe (8) and amain support mounting hole (11); the sidecar frame comprises a sidecar frame front pipe (3), a sidecar frame rear pipe (10) and a sidecar frame bottom pipe (7); three-point connection is adopted forthe connection structure: the main frame main pipe (1) is fixedly connected with the sidecar frame front pipe (3), the main frame auxiliary pipe (8) is fixedly connected with the sidecar frame rear pipe (10), and the main support mounting hole (11) is connected with the sidecar frame bottom pipe (7) by a connecting part. The connection structure effectively solves the technical problems of rapid installation and mounting and adjustment of main vehicle and side vehicle of a sidecar tricycle, and has the advantages of being accurate in installation position, smart in concept, firm and reliable,balanced and steady and low in cost.