Objective  To investigate the immune enhancement effect of different aluminum phosphate adjuvants on Streptococcus pneumococcal 9V polysaccharide (9V-PS) conjugate, and the influence of succinate buffer on immune response. Methods  Target antigen was formulated with three different aluminum phosphate adjuvants. Each formulation was further analyzed with succinate buffer. Target antigen without adjuvants was set as control group. Mice were immunized subcutaneously with prepared vaccines and serum samples were collected after each dose. Anti-9V-PS IgG antibody concentrations of the serum were analyzed by ELISA. Results  Anti-9V-PS IgG concentrations of mouse sera were not statistically significantly different among three vaccines formulated with different aluminum phosphate adjuvants (t values were 0. 38-0. 86, all P>0.05), but were significantly different (t values were 3. 75-4. 35, all P<0. 05) between vaccines formulated with and without aluminum phosphate adjuvants, higher in all adjuvant groups. Addition of succinate buffer did not affect anti-9V-PS antibody response in both adjuvants A and B groups (t values were 1. 39 and 0. 45, both P>0. 05). Conclusions  Aluminum phosphate adjuvants significantly improve immune response of 9V-PS conjugate, with no significant difference between different aluminum phosphate adjuvants. Addition of succinate buffer does not affect immune response.