The optimium value of Δν=-1 400 cm-1(Δν=1/λEx-1/λEm) for constant-energy synchronous fluorescence spectrometry was obtained by a series experiments of crude oil, crushed well-rock sand. Based on studying characteristics of constant-energy synchronous fluorescence spectra of various kinds of crude oils and natural gas from large oil fields in our country, the characteristic peak of typical crude oils were （proposed）. The main emission peak of condensation gas, light oil and dense oil was found at 276 nm, 300 nm and 330 nm respectively.
