The invention provides an indoor implementation method for obtaining a real constraint degree of a large-volume concrete structure on a temperature stress testing machine. According to the method, theinfluence of time on the constraint degree is considered, so that accurate constraint degree data can be obtained; further, the influence of a position on the constraint degree in the concrete structure is further quantified, so that a strength test can be carried out on points in the large-volume concrete structure; and furthermore, a temperature control system is additionally arranged on the testing machine, so that the temperature change of the site where the concrete structure is located can be simulated, the authenticity and reliability of a stress test made by the temperature control system are outstanding, an obtained concrete constraint stress development process and cracking characteristic can better reflect the real anti-cracking property of a dam concrete, the reliability of qualitative analysis performed through the evaluation of the concrete real crack resistance of the dam by the concrete cracking characteristic obtained in the indoor test is greatly improved, and the reliability of the temperature stress testing machine is further improved.