Abstract: In order to study the anti-cracking performance of concrete with admixtures,the load tests about the secondary lining models of different concrete were carried out under the conditions of heat and humid. It is found that anti-cracking admixtures can make strength decrease, but anti-cracking performance is improved; internal force distribution of the model are consistent; once the concrete cracks,wet and heat cycle can significantly aggravate cracking,decreasing the durability of concrete.