This paper studies a second order linear ordinary differential equation with n-turning points

Where q
1=(x-µ
1)(x-µ
2)…(x-µ
n)ƒ(x)≠0, and λ is a large parameter.The formal uniformly valid asymptotic solution of the equation is obtained based on the analysis of the three points by means of the matched method.By the work a method is developed and the applicability of this method to the n-turning points is demonstrated.