The invention belongs to the field of sealing equipment for gas isolation of furnace sections in silicon steel heat processing technology, and particularly to a sealing device for gas isolation of furnace sections, especially for gas isolation of furnace sections of a high grade oriented silicon steel continuous annealing furnace. The sealing device for gas isolation of furnace sections comprises a furnace shell steel structure and a furnace top cover covered on the furnace shell steel structure in a sealing manner, wherein refractory cast materials are internally arranged around the furnace shell steel structure; a passage allowing a steel strip to penetrate through is arranged at the middle of the furnace shell steel structure; a pair of rollers are arranged in the passage; the upper surfaces of the rollers are overlapped with the steel strip through a line; T-shaped refractory cast materials are arranged on the lower surface of the furnace top cover; a diffusing passage is arranged at the middle of the furnace top cover; two baffles are arranged on the two sides of the diffusing passage; lifting devices are arranged at the upper ends of the baffles and mounted on the upper surface of the furnace top cover. According to the sealing device, gas flow in a front furnace section and a rear furnace section can be effectively controlled, the required furnace pressure can be precisely controlled, and the required isolating effect can be achieved.