The invention relates to a natural gas pressure regulating heating system and pressure regulating heating method. The natural gas pressure regulating heating system comprises a natural gas turbine, anatural gas heater, a heat medium conveying pipe, a heat medium conveying pump and a torque transmission mechanism. The natural gas turbine is arranged on a natural gas conveying gas pipeline. The heat medium conveying pump is arranged on the heat medium conveying pipe. The torque output end of the natural gas turbine is connected with the torque input end of the heat medium conveying pump throughthe torque transmission mechanism. The natural gas pressure regulating heating system can overcome the defect that because pressure of natural gas is lowered, temperature is substantially lowered, itcan be guaranteed that the pressure of the natural gas and the temperature both meet the user requirement, and energy consumption is reduced. Besides, due to the pressure potential energy of the natural gas, the heat medium conveying pump is driven to convey heat media, inherent properties of the natural gas and the hot media are automatically coupled, it is not needed to arrange a speed regulating device to regulate the flow speed of the hot media, and the economical efficiency of the system is improved.