The proliferation of algae has had a major impact on drinking water sources, aquaculture, tourism and human health. As a kind of biological control, algae-lysing bacteria, have shown great potential in controlling algal blooms. The research group isolated a strain of Chrysosporium sp. S7 in the early stage and found that, by secreting algae-dissolving substances, the strain had obvious algae-dissolving effect on algae in an indirect way. In order to reveal its algae-dissolving characteristics and mechanism, this study, with the Microcystis aeruginosa as the target algae species, employed S7 UV-Vis, EEMs, FTIR and FCM techniques to analyze the spectral characteristics of the algae-dissolving process of Chryseobaterium sp. S7. By co-culturing the fermentation broth of the strain with the solution of algae for 7 days and by analyzing the change trend of Chla content and PC fluorescence value of algae cells through UV-Vis and EEMs techniques, the research group got the following results: the content of Chla in algae cells began to decrease on the 1st day, which indicated that the extracellular algae-dissolving substances of bacteria could quickly act on algae cells in short time, and the removal rate of Chla was 59.37% on the 7th day. In addition, the fluorescence value of PC cells in algae cells also showed a similar downward trend with the trend of Chla, indicating a decrease in Chla and PC during the algae-dissolving process. The research group found that the absorption peaks of CO, C—H and O—H bonds in the algal cell structure showed a significant downtrend at 1 647, 2 927 and 3 475~3 437 cm-1 respectively, which suggested that the polysaccharide content in algae cells and the protein structure might be destroyed, while several small absorption peaks in the range of 2 500~1 700 cm-1 further indicated the phenomenon of disintegration of algae cells. The research group also carried out PI-specific staining of algae liquid on the 3rd and 7th day, and analyzed the PI-specific fluorescence of algae cells and the auto fluorescence characteristics of Chla and PC by FCM technique. The results showed that, the PI-specific fluorescence of cells increased gradually in the algae-dissolving process of bacteria S7, and the autofluorescence of Chla and PC showed a downward trend, indicating that the damage degree of algal cell membrane, Chla and PC had a close internal relationship with each other and high consistency in the algae-dissolving process. During the algae-dissolving process, the algae cells showed various forms of damage, and the damage was in the process of dynamic change, with the Q1 (Q5) quadrant cells gradually moving to the Q4 (Q8) quadrant cells in sequence. Therefore, the possible algae-dissolving process of Chryseobaterium sp. S7 could be speculated as follows: The bacteria release the algae-dissolving active substance to the outside of the cell, and the algae-removing active substance changes the structure and permeability of the algal cell membrane by destroying the structure of the polysaccharide and protein in the cell membrane of Microcystis aeruginosa, which will further destroy Chla in the cell body, PC, DNA/RNA and other substances. All these will cause the algae to lyse and die, eventually forming cell debris. This study, by analyzing the crystallization characteristics of algae cells in the algae process of Chryseobaterium sp. S7, reveals the algae-dissolving mechanism of algae-lysing bacteria, and thus provides a theoretical basis for microbial algae control and restoration technology.