Biological safety system suitable for building pig farm

The utility model discloses a biological safety system suitable for building pig farms, which comprises a red area, an off-site biological safety preposed defensive line, an orange area, a first defensive line, a yellow area, a second defensive line and a green area which are sequentially arranged from outside to inside, the protection levels of the red area, the orange area, the yellow area and the green area are sequentially improved, and the red area, the orange area, the yellow area and the green area only can realize one-way circulation. The green area comprises an internal area in which pigs or personnel move in production units and connecting parts in the production line and which is physically isolated from the yellow area, the yellow area comprises an in-site living area and an area, except the green area, of the production area, and the orange area comprises an area from a building pig farm wall to an area within an off-site biological safety preposed defense line; and the red area comprises an area