In this paper, the single-factor and Box-Behnken experiments were employed to optimize the extraction parameters of intracellular polysaccharide (IPS) from Penicillium camemberti, i.e. liquid-solid ratio, extraction time and temperature, and the antifreeze activity of IPS was also evaluated. The results showed that the IPS could be best extracted with liquid-solid ratio 36.71 (mL/g) at 89.6 ℃ for 123 min, and the yield of it was about 12%. In addition, the antifreeze activity of IPS was almost equal to glycerol, and the livabilities of Bifidobacterium breve, Bifidobacterium infantis, Bifidobacterium bifidum were significantly improved by 1%~2% IPS.