The invention discloses an automatic liquid nitrogen fire-extinguishing and explosion-suppressing system for an oil tank region. The automatic liquid nitrogen fire-extinguishing and explosion-suppressing system comprises a liquid nitrogen storage station, a low-temperature liquid nitrogen booster pump and a monitoring-jetting integrated box, wherein the monitoring-jetting integrated box comprises a housing, a glass ball expansive type constant-temperature fire detector with a glass ball fracture free surface, an expanding cavity and a horn-shaped outlet; the glass ball expansive type constant-temperature fire detector, the expanding cavity and the horn-shaped outlet define a low-temperature nitrogen gas cavity; the top of the liquid nitrogen storage station is connected with a self-lifting buffer tank through a gas exhaust interface; the self-lifting buffer tank communicates with the low-temperature nitrogen gas cavity through a housing upper interface; the low-temperature liquid nitrogen booster pump is connected with an inlet of a low-temperature ball valve; an outlet of the low-temperature ball valve is connected with the glass ball fracture free surface through a rear section of a gas storage tube; a connecting line is arranged on the rear section of the gas storage tube; a pressure feedback device, a fire-fighting linkage controller and an alarm are sequentially connected on the connecting line; and the alarm is connected with a control end of the low-temperature ball valve. The system can solve the fire efficient response problem, the liquid nitrogen effective conveying problem, the liquid nitrogen efficient atomizing problem and the liquid nitrogen diffusing problem, so that the purpose of automatically and efficiently suppressing explosion and extinguishing fire in an oil tank is achieved.