Abstract: Risk assessment has been widely applied in many industrial fields since it raised in the 80's of last century. At the same time, risk assessment of pipeline has well developed gradually. Of many risk assessment methods of pipeline, W. Kent Muhlbauer's index method is the most reliable, but it also has some disadvantages. W. Kent Muhlbauer's method is improved in this paper, and the improved method is used to evaluate the high-pressure pipeline in Natural Gas Utilization Engineering in Nanjing City. The indication of the assessment results is identical with results in relative article and clearer, straightforward.