In order to know the relation between the bending and temperature of coated steel beam in fire test, the authors carried out a certain amount of fire tests for coated steel beams. Through the analysis of testing data it can be seen that the bending and temperature of coated steel beam are closely related, and the time when the bending at the mid-span of the beam exceeds L 2 /400d mm is almost the same as that when the average temperature of the beam rises to 538 under the condition that the beam is subjected to a total load which represents 60 % of the design moment resistance.