Abstract: The Finite Analytic Method (FA)is an efficient numerical method to solve the fluid flow problems . However, the calculation of Finite Analytic Coefficients by the conventional method is bored and time consuming . Moreover,in some extreme cases the resulted coefficients may become totally erroneous. This paper presents an approximate formula to determine FA coefficients . which is convenient to use. The error caused by the approximaion is less then 0.003.

Key words: Finite Analytic Method, approximate formula, convection-diffusion equation