Effect of the different types of precipitates and precipitation-dissolution behaviors on austenite grain growth in reduced activation ferritic/martensitic(RAFM)steel was studied by using metallography and Transmission Electron Microscope(TEM).In order to investigate the pinning effect of M23C6 and MX precipitates on austenite grain growth,austenitizing experiments were carried out at 900 °C and 1200 °C with the various holding time.Experimental results show that the austenite grain size increases with the enhancement of heating temperature and holding time.Increasing holding time at 900 °C causes M23C6 precipitates coarsening and then dissolving at a slow rate,while MX precipitates keep stable.