The invention discloses an infusion system integrating heat preservation, heating and automatic alarm. The infusion system comprises a sleeve bag, resistors, a thermistor, a liquid crystal display, areflection type photoelectric switch, a PLC, an infrared temperature sensor, an alarm device, a plug and a nurse station signal receiving device and is characterized in that the sleeve bag sleeves aninfusion bag during infusion, the resistors and the thermistor which are serially connected are distributed all over the sleeve bag, the liquid display is arranged in the middle of the sleeve bag, andthe reflection type photoelectric switch is arranged at the bottom of the sleeve bag; when the infusion system is power-on, the resistors distributed all over the sleeve bag starts heating, an infrared temperature sensor at the bottom of a bag opening detects the temperature of liquid medicine in the infusion bag, converts a temperature signal into an electric signal and transmits the electric signal to a PLC analog quantity special module, the electric signal is converted into digital quantity which is transmitted to a PLC data storage, the signal is transmitted to the liquid crystal displayfor displaying, and temperature needed by a patient can be achieved by using the PLC to perform certain operation and conversion; when the liquid medicine is about to run out, the reflection type photoelectric switch which is used for monitoring the liquid medicine and connected with the alarm device is triggered to transmits a signal to the nurse station signal receiving device.