Abstract:To reveal the rule of high strength concrete stress under the influence of hygro-thermal coupling and the cracking risk, the calculation method of hygro-thermal coupling and the calculation method of early age restraint shrinkage stress were established taking the concrete prism as an example. The simulation of temperature and humidity field was realized by programming. The results show that the model of hygro-thermal coupling can predict the development of temperature and humidity change in the early age of high performance concrete from 1day to 28 days. Under the condition of watering, the hygro-thermal coupling effect has little effect on the temperature field, humidity field and stress of high performance concrete, and the restraint stress and cracking risk are growing rapidly after stoping curing. The curing and atmosphere have remarkable influence on the early ages stress and cracking risk for high strength concrete.