Abstract: The three types of decline curves presented by Arps(i.e. Exponential decline, Hyperbolic decline, and Harmonic decline)has been applied extensively in reservoir engineering. They are used to predict future production rate and recoverable reserves of oil and gas reservoirs. However the result their valid prediction can be obtained only when the exact type is identified. Generally three methods of determining are used today to identify the type of decline curve namely: (1) Curve shifting method; (2) Trail and Error method; and (3) Type curve matching method. However, the results obtained by either of these methods are nonunique to some degree. A New method of identify the type of decline curves i.e. the method of dual regression analysis is presented in this paper, which can give a unique result. A program on a PC-1500 pocket computer is presented in this paper.