A vaccine oil adjuvant. The vaccine adjuvant of the invention comprises a hydrolyzed &bgr -glucan with a weight average molecular weight of about 10000 to 1000000. The hydrolyzed &bgr -glucan in an amount of between 0.1mg/ml and 10 mg/ml by weight of the vaccine adjuvant is dispersed in the aqueous phase which is homogenized with the oil phase using various emulsifiers. The vaccine adjuvant of the invention may improve the protection titer and elongate the protection period of the vaccine.
