An energy-saving ventilation system using process exhaust air, the system comprising: a fresh air handling unit configured to handle outdoor fresh air and then supply handled outdoor fresh air to a production room; an exhaust air recycling device configured to transfer available process exhaust air itself and/or energy of the available process exhaust air in the production room back to the production room and/or an air inlet of the fresh air handling unit; characterized in that the exhaust air recycling device comprises a process exhaust air recycling unit configured to recycle and transport the available process exhaust air in the production room back to the production room; wherein the process exhaust air recycling unit comprises: an air inlet section connected to an outlet of the production room for exhausting the available process exhaust air, an air outlet section connected to an inlet of the production room for receiving the available process exhaust air, and a fan section located between the air inlet section and the air outlet section; the system further comprising a connection air pipe, wherein one end of the connection air pipe is connected to the air outlet section and another end of the connection air pipe is connected to the production room; wherein the system further comprises an air outlet section air pipe, wherein the connection air pipe is provided with a first electric seal valve, one end of the air outlet section air pipe is connected to the connection air pipe between the air outlet section and the first electric seal valve, another end of the air outlet section air pipe is connected to atmosphere outside the production room, the air outlet section air pipe is provided with a second electric seal valve, a portion of the connection air pipe between the air outlet section and the first electric seal valve is provided with a hazardous substance probe, the hazardous substance probe is connected to a controller by signal, and the controller is connected to the first electric seal valve and the second electric seal valve by signal respectively to control opening and closing of the first electric seal valve and the second electric seal valve respectively; when the hazardous substance probe detects a hazardous substance in the connection air pipe, the controller controls the first electric seal valve to close and the second electric seal valve to open. a fresh air handling unit configured to handle outdoor fresh air and then supply handled outdoor fresh air to a production room; an exhaust air recycling device configured to transfer available process exhaust air itself and/or energy of the available process exhaust air in the production room back to the production room and/or an air inlet of the fresh air handling unit; characterized in that the exhaust air recycling device comprises a process exhaust air recycling unit configured to recycle and transport the available process exhaust air in the production room back to the production room; wherein the process exhaust air recycling unit comprises: an air inlet section connected to an outlet of the production room for exhausting the available process exhaust air, an air outlet section connected to an inlet of the production room for receiving the available process exhaust air, and a fan section located between the air inlet section and the air outlet section; the system further comprising a connection air pipe, wherein one end of the connection air pipe is connected to the air outlet section and another end of the connection air pipe is connected to the production room; wherein the system further comprises an air outlet section air pipe, wherein the connection air pipe is provided with a first electric seal valve, one end of the air outlet section air pipe is connected to the connection air pipe between the air outlet section and the first electric seal valve, another end of the air outlet section air pipe is connected to atmosphere outside the production room, the air outlet section air pipe is provided with a second electric seal valve, a portion of the connection air pipe between the air outlet section and the first electric seal valve is provided with a hazardous substance probe, the hazardous substance probe is connected to a controller by signal, and the controller is connected to the first electric seal valve and the second electric seal valve by signal respectively to control opening and closing of the first electric seal valve and the second electric seal valve respectively; when the hazardous substance probe detects a hazardous substance in the connection air pipe, the controller controls the first electric seal valve to close and the second electric seal valve to open.