The invention discloses a method and a device for quench determining and switching control of a high-temperature superconducting transmission line. The method comprises steps that: the three-phase shielding layer current, the conductor layer current and the cable refrigeration system state data of the high-temperature superconducting cable in operation are acquired; the phase distance between anytwo phases of the high-temperature superconducting cable can be acquired; the three-phase shielding layer resistance of the high-temperature superconducting cable can be calculated to determine whether the shielding layer is quenched under a three-phase line short-circuit fault; whether a superconducting cable refrigeration system fault occurs is determined according to the collected cable refrigeration system state data; when the shielding layer is subjected to quench or the superconducting cable refrigeration system fails, a tripping instruction is output to cut off the superconducting lineand transfer the power supply of the standby line. The invention is advantageous in that the superconducting cable quench detection method based on the electrical quantity and the non-electrical quantity is comprehensively applied, the online monitoring and determining of the cable quench or the cooling system fault caused by the system short-circuit current can be realized, and the reliability and the accuracy of the superconducting cable quench detection can be improved.