Abstract: Transporting different oil products sequentially in the same pipeline is an important operation. In such case, mixture of two oil porducts is unavoidable. What is required of the administrative and operating personel is that they must know very well the mixing law, accurately calculate the quantity of the mixed oil, and cut it off in time. However, the theory of oil mixture is very complicated, and so is the calculation process. In order to overcome this kind of difficulty, we have, in light of the documentary formulas, made out the general programme for theoretical and practical calculation of sequential transport of two oil products by microcumputers, which has two versions, English and Chinese, with the results displayed either on the screen or typewritten.