Reference Cost Theory is proposed by one of the authors when he took charge of the State Key Research Project "the Research on National Phosphorus Resource Exploitation System",which won the second prize of National Science and Technology Progress.Based on Reference Cost Theory,this paper proposes Reference Cost Model,which is a new way to estimate the commercial residential building cost under some uncertainties,incomplete information and lack of the cost composition list.Reference Cost Model will enlighten the housing authorities about how to publish the residential building cost and help customers to make right purchasing decisions.In empirical analysis,we estimate the cost of certain residential project in Beijing using Reference Cost Model with public information.