Abstract: The forecast model about the compressive strength of recycled aggregate concrete was set up using the method of BP neutral network. The model was threelayer network structure pattern. The inputtinglayer was the mix ratio of recycled aggregate concrete. The outputtinglayer was the strengths data of the recycled concentrate in 7, 28, 56, 90 d. The model’s transfer function was Sigmoid function.Because the numerical value of Sigmoid was in [0,1]. This article turned the inputting data into the data in [0,1]. At last, the experimental work for the compressive strength of recycled aggregate concrete was designed and performed with 33 pieces. The model was trained and tested by experimental data.It showed that forecast result was match with test results and it could be referenced for experimentation and manufacture.