The invention belongs to the technical field of vaccine preparation, and particularly provides a streptococcus suis type 2 attenuated strain and an application thereof. The streptococcus suis type 2 is streptococcus suis type 2-XN, and the preservation number is CTCC NO:M2017003. A vaccine prepared from the strain is capable of preventing a disease caused by the streptococcus suis type 2, the immune protective effect on homologous serotype reaches more than or equal to 90%, stress reaction is not generated to the organism, the streptococcus suis type 2 attenuated strain can be applied to swine streptococcosis prevention of breeding pigs and piglets in a pig farm, the incidence rate of the swine streptococcosis of the pig farm is reduced and the survival rate of the piglets is improved.