The invention discloses a low temperature superconducting magnet joint lap joint soldering technology which comprises the steps of single joint copper surface tin-plating and double joint lap joint soldering. Compared with a traditional joint lap method, the technology provided by the invention has the advantages that through single joint copper surface tin-plating, a tin material can completely infiltrate and cover the copper surface of a joint, and oxide and impurities in the tin material can be easily removed; when double joint lap joint soldering is carried out, new solder and flux are not added, and flux and oxide residues on the joint contact surface are prevented; double joint lap joint uses automatic pressurization and heating equipment, which realizes precise control of heating and pressing rate of a lap joint process; and the technology has the advantages of high field operability, high joint reliability, low contact resistance and high contact strength.