Abstract: Currently, urban rail transit projects have clear cost breakdown of open excavation tunnel, while railway and municipal engineering doesn′t have, which is insufficient to meet the demand of large scale engineering construction. After analyzing the costs of completed open excavation tunnels, it is found that the proportion of materials is high, while the proportions of labor and machine costs are relatively low. Considering the terms of current code, it is suggested that the cost of railway open excavation tunnel should be handled according to the rate of Class 10 in the "Budgeting the Cost Quota of Basic Design for Railway Projects". The estimating method of municipal tunnel cost is suggested to operate in line with urban rail transit projects.