Abstract: In the theory of conjugate surfaces, the principle of equidistant conjugate surfaces is very important. Applying the principle, the meshing on a conventional point is converted to that on a point on the pitch surface; therefore this problem is greatly simplified. But nobody has discussed this principle before. In this paper the conception of equidistant conjugate surfaces is offered, their conjugate characteristic is proved, and the corresponding formulas are given. The principle of equidistant conjugate surfaces may find many applications. The authors take "SGM" as an example to explain that basing on the research of E. Wildhaber and applying the principle, various sheets for setting computation are given.