The invention discloses a band-gap reference source starting circuit. The starting circuit comprises three PMOS transistors, a comparator, two triodes, four resistors and an NMOS transistor. Based onan existing band-gap reference source starting circuit, the NMOS transistor is additionally arranged between the second resistor and a ground wire, the drain electrode of the NMOS transistor is connected with the second resistor, the source electrode of the NMOS transistor is grounded, and the gate electrode of the NMOS transistor is connected with the output end of the starting circuit. Degenerate point of triode zero current can be avoided through the band-gap reference source starting circuit.