The invention provides a multivalent pneumococcus capsular polysaccharide-protein conjugated composition and a preparation method thereof. The conjugated composition is formed by covalent linkage of multivalent pneumococcus capsular polysaccharides of 14 different serotypes and carrier protein, wherein the 14 serotypes include 1, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19A, 19F, 22F, 23F and 33F. The conjugated composition has good adsorption effect and good stability, has multiple immunogenicity and protective performance against invasion of the pneumococcus of 14 serotypes, is superior to on-sale low-valent pneumonia compositions, and the immune response of the conjugated composition disclosed by the invention is higher than that of an uncombined composition. The inoculating injection frequency can be reduced by using the multivalent pneumococcus capsular polysaccharide conjugate vaccine containing the conjugated composition, the immune process can be simplified, and diseases of human and animals caused by the 14 serotypes of pneumococcal bacteria can be effectively prevented. The conjugated composition has wider coverage and better immune effect.