The utility model relates to a modular gigabit industrial Ethernet switch. A standard 19-inch chassis is adopted, and an upper cover plate adopts a single-rib design, so the cooling area of the industrial switch is increased, and the industrial switch can work in the temperature between -40 and +75 degrees. 101-104 in a back panel are four detachable board cards capable of freely combining, so different requirements of clients to optic electric interfaces can be satisfied. Four gigabit optical ports (0-4 gigabit optical ports can be selected according to the requirements of the clients) are in a fully closed structure, and the access mode of a power supply can be selected according to the different requirements of the clients, so the requirements of a harsh industrial site can be greatly satisfied.