Abstract:The calculation formulas of main transmission chain’s structural formulas had been studied in this article from the point of view of the theory on the enlarging manners and orders of systems. The result of research indicates that a general formula for the calculating of the transmission of machine tools can be obtained only if a small change is made for the existing one. Using this new formula, not only the rotational speed series of the machine tools can be easily acquired, but also both theirs structural formula and network visually (visual?) correspondence. Compared with the traditional ones, it is convenient to use, and has significance meaning in practice both in the form and content. So it provides a reliable theoretical formula for the calculation of the main transmission system of machine tool.