The effects of low atmospheric pressure on the properties and hydration process of cement-based materials were studied by strength tests， X-ray scanning and comprehensive thermal analysis. The results show that the low curing atmospheric pressure delays the cement hydration process， the generation of hydration products decreases， and the lower the curing atmospheric pressure， the more significant the impact effect. An obvious hydration plateau period appeares at the age of 3-7 days. Under the low curing atmospheric pressure， the pore structure of the cement-based marerials deteriorates， and the proportions of gel pore growth is the largest. The lower the curing atmospheric pressure， the higher the water absorption rate， and the greater water absorption amount. However， the water absorption， water absorption rate and relative water absorption rate of the cement-based marerials all decrease significantly with the decrease of environmental atmospheric pressure.