In this paper, the COD standard liquid is used as the research object, and the water COD is detected by the chemometrics algorithm based on the fluorescence emission spectrum data of specific excitation wavelength. During the detection process, the influences of temperature, turbidity and pH on the fluorescence spectrum are analyzed, and the compensation correction is performed on the influence of the related parameters. Firstly, excitation-emission matrix (EEM) spectra of the COD standard solution whose concentration ranges between 1 and 55 mg·L-1 are collected by fluorescence spectrophotometer, after the scattering peaks are removed, the partial least squares based on the ant colony (ACO-iPLS) algorithm is used for extracting feature for the fluorescence emission spectra (Em=275～450 nm) at different excitation wavelengths (Ex=255～285 nm, with the interval 5 nm) and the least squares support vector machine algorithm with particle swarm optimization (PSO-LSSVM) is used to establish the prediction model. The results show that the determination coefficient of the validation set (R2p) of the fluorescence emission spectrum data model at different excitation wavelengths is within the range of 0.961 8～0.998 1, of which the effect of the fluorescence emission spectrum data model at Ex=270 nm is the optimal, and the determination coefficient (R2p) and the root mean square error of prediction (RMSEP) are R2p=0.998 1, RMSEP=0.348 3 mg·L-1, respectively. Secondly, the influences of temperature, turbidity and pH on the water COD detection by fluorescence spectrometry are analyzed, and the corresponding compensation model is obtained. The results demonstrate that the effect of temperature and turbidity on the fluorescence spectrum cannot be ignored, but the compensation model can be established to correct the interference effectively. The mean deviation (Bias) of fluorescence model after temperature compensation is 0.130 6 mg·L-1, and the influence of turbidity change on COD detection by fluorescence spectrometry can be well corrected after turbidity compensation, while the effect of pH range in 4～12.3 on the fluorescence spectrum is relatively small, so it can be ignored. Finally, combined with the analysis results of single influence factors, the effects of various environmental factors (temperature, turbidity and pH) on the detection of water quality COD by fluorescence spectrometry are analyzed. The result shows that after neglecting the influence of pH, the influences of temperature and turbidity on the fluorescence spectrum can be corrected effectively. The results of the paper can serve as reference for water quality parameter optical sensors in suppressing environmental factors during commissioning.