中文摘要：

BP算法神经网络是一种曲线拟合方法，因为其内在的自适应性，可以以任意精度逼近非线性系统。通过曲线拟合能够较好地反映社会自然现象的本质。把这一理论应用于美国人口预测模型，体现了BP神经网络在人口估计中的优越性。

英文摘要：

BP Algorithm neural network is an important curve fitting method. For the inner self-adaption, the solution can reach to ture value in the way of any precision, and BP method can reflect the essence of social or natural phenomenons. The BP thoery is applied to U.S. population Forecast ,which expressed the the superiority of estimated population.