The invention discloses a shutdown and protection circuit for a PFM synchronous boost DC-DC converter. An enabling true shutdown circuit and short protection circuit comprises a maximum potential selection circuit, a substrate potential selection circuit of a PMOS transistor MP and a start and short protection circuit, wherein the substrate potential selection circuit of the PMOS transistor MP selects high potential in a power conversion end LX and output VOUT to be connected with a substrate of the PMOS transistor MP according to an input logic signal V-control, thereby achieving true disconnection between input VBAT and the output VOUT when enabling is shut down or the output is shorted. When the output VOUT of the start and short protection circuit is shorted to ground or the start state is smaller than the input VBAT, a gate of the PMOS transistor MP is controlled by the output and current of the PMOS transistor MP is a set value; and short current is fixed when the output VOUT isshorted, thereby achieving short protection and avoiding the damage to the synchronous rectifying PMOS transistor MP.