The conjugates of present invention are formed by the combination of rhein or their analogues with the organic bases or amino acids in molecular force between them. The methods for preparing the conjugates and their uses for manufacturing medicines in the treatment of diabetic nephrosis, recovery of gastrointestinal function and prevention of intestinal adhesion, as well as treatment of osteoarthritis, rheumatic arthritis and rheumatoid arthritis are also described. Rhein or their analogues as the left part of general formula (I) is selected from (1) the compounds of rhein or their analogues, in which one or two substituents of R2˜R3 and R6˜R7 are COOH at least two substituents of R1˜8 are —H; or (2) the rhein-containing extract derived from plants. In general formula (I), M represents nitrogen-containing organic bases or basic amino acids.