The classical Mie theory was used to exactly describe the field inside the sphere in the interaction between the parallel beams and microsphere particles.If the particle size and the imaginary part of the refractive index are large,The data overflow by the calculation of radial function for an absorbing microsphere particle will appear,which leads to the failure of the calculation,and the unreasonable results are obtained.In order to overcome the overflow,an algorithm was proposed by introducing modified radial functions so as to keep their values in an appropriate range.Numerical calculations were conducted and reasonable results were obtained.The results demonstrate that the algorithm can overcome the data overflow successfully,and it can also be used to calculate any internal field of microsphere particles interacting with various parallel optical beams.