Abstract: There is a difficulty in social economic benefit post-evaluation facing to highway developments item in China. This paper, using the system engineering theories and methods, puts forward to make use of a Grey system model to quantify social economic benefit. On the basis of the project of Xiamen Haicang Bridge，we use buffer operator in grey system theory，set up Model GM(1,1)and grey-linear regression combined model to analyze time sequence. The case study shows that the proposed method is feasible.

Key words: social economic benefit, grey-linear regression combined model, Model GM(1, 1), buffer operator

摘要： 运用系统工程理论方法，针对目前我国公路建设项目后评价工作中所面临的社会经济效益定量评价这一难题，提出当统计数据缺乏的情况下选择、运用灰色预测模型对指标进行定量分析、预测的新思路；以厦门海沧公路大桥项目为背景，结合定性分析，采用灰色系统理论中的缓冲算子公理，建立了GM(1,1)模型和灰色线性回归组合模型对数据进行拟合和预测，取得了满意的结果.

关键词: 社会经济效益, 灰色线性回归组合模型, GM(1, 1)模型, 缓冲算子