In order to resolve that information project fund is difficult to estimate in demonstration, need to get a method of estimating that does not depend on the developer or the third party. This paper provides an estimation model based on the theory of life cycle cost, then taking the finished information projects as sample, a linear regression model is built to calculate software development cost, and it gives an example of application. The result shows that this method is independent, objective, simple and practical. In the future demonstration project, this method is feasible.