The invention relates to a quench-detection circuit of a high-temperature superconducting magnet, in particular to a circuit for detecting whether quench occurs to the high-temperature superconducting magnet or not. The circuit comprises the high-temperature superconducting magnet, a correction circuit, an optocoupler isolation circuit, a differential operational amplifier circuit, an absolute value circuit, an analog multiplication circuit, a current-voltage conversion circuit, a filter circuit, comparison circuits, an output circuit, and the like, wherein, the high-temperature superconducting magnet is formed by connecting a plurality of high-temperature superconducting coils in series, each two high-temperature superconducting coils are taken as one group for carrying out the comparison, output ends of each group of the comparison circuits are connected in parallel, a quench signal is output, and the quench signal is input to a protection circuit, thereby avoiding the high-temperature superconducting magnet from being damaged.