The molecular structure of modified Rhodamine-6G is complex, and it is easy to decompose. In order to reduce the fluorescence back-bottom of Raman spectrum and improve the stability of signal, the influence of laser wavelength , intensifier proportion, stabilization time, spectral acquisition and other parameters were optimized and analyzed in this paper, and the optimal test conditions were determined: laser wavelength(785nm), intensifier proportion (V sample:V intensifier=2:1), stabilization time of enhancer and sample after mixing(0.5h), spectrum conditions(collection spectrum time 10s, integration times3 ). Under these conditions, the concentration standard solution(100-250mg/L) was tested with three parallel samples. The response value and concentration curve were established with the F1 peak area as the response value, and the concentration linear equation was obtained. The linear correlation coefficient of this method was 0.968, the standard deviation was 3.85%, and the detection limit was 25mg/L, which indicated that this method could be used for the determination of rhodamine-6G concentration. Under light dyes, its concentration and characteristic peak change was determined, the results show that with the increase of time, the dye concentration drops rapidly, as the same time HF1:F2 peak height ratio decreased, F1 relater to C-F bond, and F2 relater to xanthene bond, during the decomposition process, xanthene bond main chain and C-F bond side chain rupture and the C-F bond is more likely to break.