Abstract: Analyzed here in the paper is the effect by the heat treatment temperature and holding duration on microstructure and hardness of the cold-rolled GH2747 alloy seamless tube. As a result it is revealed that the grain size of the GH2747 alloy is enlarged along with rising up of the heat treatment temperature and extension of the holding duration;the apparent activation energy for the grain enlargement of the alloy is 234.9 kJ/mol;that the said grain size enlargement as per the holding duration is in compliance with the Baker Formula,and the dynamic time index η shows a trend of being invariable at first,and then decreasing along with the increase of the temperature;and the Vickers hardness HV and average grain size of the GH2747 alloy under the condition of different heat treatment process parameters are in accordance with the Hall-Petch Relationship.