The invention relates to the field of circuit fault detection and discloses a method and device for detection of a circuit fault in a contact net. The method and device are used in monitoring equipment. The method comprises the steps that detection information of a circuit in the contact net sent by a detection terminal is received; the detection information comprises current values of the circuit in the contact net; whether the fault takes place in an uplink or a downlink is determined according to the received detection information; in the determined uplink or downlink with occurrence of the fault, the current values in the detection information sent by the two adjacent detection terminals are compared; and an area between the two detection terminals of which the current values in the sent detection information have the largest difference is determined as a fault area. The method and device disclosed by the invention can comprehensively analyze detection data at multiple positions in the contact net so as to increase accuracy of fault positioning.