Abstract: To monitor the transient temperature field of boiler drum, a calculation model was set up based on inverse method, with which the transient temperature was obtained by solving the ordinary differential equations transferred from partial heat conduction equations using inverse method with volume control ideas according to the temperature measured by thermocouples mounted on outer surface of the drum. The calculation results were verified by one-dimension heat conduction analytical solutions and two-dimension heat conduction Ansys numerical solutions for infinitely long cylinder as well as by experimental data. Results show that there is a good agreement among above three calculation methods, proving the inverse method to be highly accurate, which therefore can be used in on-line transient temperature monitoring of boiler drums.