The invention discloses a fire extinguishing protective system for a passenger compartment of a bus. The fire extinguishing protective system comprises a water mist spraying device, a fire extinguishing device and a starting device, wherein the water mist spraying device comprises a water storage tank, a first transmission pipeline and a first water mist nozzle; the first water mist nozzle is installed at the top part on the inner side of the bus and is connected with the water storage tank by virtue of the first transmission pipeline, the water storage tank is connected with a power mechanism; the fire extinguishing device comprises a water mist fire extinguishing mechanism and/or a gas fire extinguishing mechanism, wherein the water mist fire extinguishing mechanism comprises a second transmission pipeline and a second water mist nozzle, and the second water mist nozzle is installed at the bottom of the passenger compartment wall of the bus and is connected with the water storage tank or another water storage tank by virtue of the second transmission pipeline; the gas fire extinguishing mechanism comprises a fire extinguishing agent vessel, a fire extinguishing agent transmission pipeline and a fire extinguishing agent nozzle, wherein the fire extinguishing agent vessel is filled with a gas fire extinguishing agent, and the fire extinguishing agent nozzle is installed at the bottom of the passenger compartment wall of the bus and is connected with the fire extinguishing agent vessel by virtue of the fire extinguishing agent transmission pipeline; the starting device comprises a main controller, and the main controller is connected with a starting button and/or fire detector.