The invention discloses a lithium ion battery system with a safety device. The system comprises a battery box, a battery box cover plate matched with the battery box, and a battery module mounted in the battery box through a mounting assembly, wherein the mounting assembly comprises a cylindrical grid rib plate mounted in the center of the battery box, a rubber ring is arranged on an inner wall ofan opening on an upper end of the grid rib plate through efficient fireproof glue in an adhering mode, the grid rib plate abuts against an upper top surface of the battery module and is used for limiting a battery module, a fireproof ring is arranged outside the grid rib plate in a covering mode, the fireproof ring is filled with a plurality of suspension type superfine dry powder fire extinguishing devices, and temperature sensing glass spray heads of the suspension type superfine dry powder fire extinguishing devices penetrate through an inner wall of the fireproof ring to be obliquely arranged. The system is advantaged in that the system is provided with fire extinguishing equipment, so damage caused by explosion of the lithium battery can be reduced as much as possible, and fire disasters of a lithium battery are reduced.