To correct the defects existing in the common parametric or non-parametric estimating methods, this research presents a theoretical production function estimating approach based on DEA, and it can effectively estimate the parameters included in the concave production function. The theory is basically working in the follow way: Firstly, get the (weak) efficient DMU from the evaluation of each DMU' production efficiency by the method of DEA; Secondly, determine the efficient frontier of the production possibility set based on each (weak) efficient DMU,and then provide the least upper bound (LUB) of the theoretical production function by the applications of the linear approximation; Finally, calculate the parameters included in the production function, thereby obtain the concrete form of production function. This research uses the C-D function as an example for calculation to demonstrate the advantages of the approach proposed.