The invention discloses an immunoturbidimetry kit for detecting streptococcus agalactiae and a detection method of the immunoturbidimetry kit. The immunoturbidimetry kit comprises a reagent I, a reagent II and a streptococcus agalactiae standard product, wherein the reagent I is a phosphate buffering solution containing 1.5%-2% of polyethylene glycol at a mass/volume ratio and the pH (Potential of Hydrogen) value of the reagent I is 7.38-7.42; the reagent II is an 0.02%-0.04% anti-mouse human streptococcus agalactiae monoclonal antibody emulsion particle at a mass/volume ratio; the adding ratio of the reagent I to the reagent II in a reaction system ranges from (2.5:1) to (3:1) at a volume ratio. The kit and the detection method are established on the basis of antigen antibody combination; a streptococcus agalactiae monoclonal antibody is coupled with emulsion and the adding ratio of the reagent I and the reagent II in the reaction system is adjusted so as to realize rapid and high-sensitivity detection of the streptococcus agalactiae; the kit and the detection method are simple, convenient and rapid to operate, easy in result judgment and free from influences of personal error factors.