Abstract:In sphere surface fitting, the errors in the coefficient matrix and observation vector are from the same place, which is the coordinate of the spherical point.The same elements exist in different places.These same elements ought to have the same corrections.The linear form appears in the observation vector.Therefore, an improved total least squares algorithm is deduced which can overcome the above problems.Through analysis of examples,we discover that the parameters obtained from the method in the paper are more reliable.This demonstrates that the method is feasible and effective.