Abstract: The transient thermal effect of a tilting pad thrust bearing in the operation process with sudden variation in load and at different rotational speeds has been experimentally investigated. The results indicate that the temperature of oil film and the temperature of the entrances and outlets of the pad increase and the mean oil film thickness decreases with the sudden increase of the carrying loads. The rising amplitude of the oil film temperature increases and the decreasing amplitude of the mean oil film thickness increases with the increase of the load variation. The variation amplitude of the oil film temperature is larger at higher running speed, and the diminution amplitude of the mean oil film thickness is smaller at higher running speed under the same load variation.