Abstract: The essence of energy level fluctuations lies in the deviation of quantum distribution law from its classical counterpart which is usually considered as a smooth average of energy level data.It is the key-work to find an optimam fitting curve of original level data for the unfold of energy level fluctuatione thereby.This article is devoted to discribe the fundamental ideas concerning with energy level fluctuations and their unfolding, meanwhile to put forward a fitting method of polynomial expansion which is more universal for unfolding energy level fluctuations by means of a synthesis of different unfolding methods for various spectra.The arguments formed in this article is clarified by concrete treatments for some typical examples.

Key words: Statistics of energy level fluctuations, Fluctuations unfolding, Polynomial expansion fitting