The invention belongs to the technical field of circuit diagnostics, and particularly relates to a detecting device of a 900v high voltage leakage current. The detecting device of the 900v high voltage leakage current comprises a positive wire, a negative wire, leakage current sensors and a single chip computer connected with the leakage current sensors, wherein the positive wire and the negative wire are respectively connected with a load in an electric circuit, and the leakage current sensors are respectively arranged on circuits of the positive wire and the negative wire, which are connected onto the load. The technical scheme includes that the detecting device of the 900v high voltage leakage current can detect electric leakage status on an armored car in quantificational mode, reads out voltage through the leakage current sensors, and sends the electric leakage voltage to the single chip computer, the single chip computer performs A/D (analog to digital) acquisition and processing and figures out the leak current, and when detects that value of the leak current is larger than 50mA and duration of the leak current is 200ms, the single chip computer sends an electric leakage alarm signal to an upper computer, and corresponding safeguard procedures are implemented according to information fed back by the upper computer. The detecting device of the 900v high voltage leakage current is simple in diagnosis circuit, and can not influence a detected object.