A new analytical approach for solution to the overdetermined equations of the quasi-continuous potential and field profiles of the reverse-biased p-n junctions with the elliptical cylindric coordinates is proposed in the paper.The dimensional transformation and the searching algorithm for two-interpolation and standing point are used in least-squares for increasing in calculation precision and ameliorating nonsingularity and ill-condition of the symmetric positively semidefinite matrix caused by nonlinearity of the potential and electrical field.