The invention discloses a multifunctional knapsack which comprises a body. A zipper for closing up and assembling the sides of the knapsack in a pulling mode, fastener hooks, a tent ring lining belt, a tent ring and a tent supporting rod bag are arranged on the body. The body forms a sleeping mat after the zipper for closing up and assembling the sides of the knapsack in the pulling mode is pulled open and unfolded. Tent supporting rods are arranged in the tent supporting rod bag, the tent supporting rods, the tent ring lining belt and the tent ring form a tent support when the body is unfolded, supporting rod loops connected with the tent supporting rods are arranged on a raincoat, and the raincoat covers the tent support to form tent awning cloth. The fastener hooks of the unfolded body adhere to fastener loops on the raincoat to form a tent ground mat. The multifunctional knapsack is simple in structure and convenient to combine and can serve as the sleeping mater after being unfolded, and the raincoat can be combined with the multifunctional knapsack to form a single mat. The multifunctional knapsack is suitable for combat training of troops and can be also suitable for outside travel, camping, picnics and other occasions of people.