Aiming at the existing problems of traditional tunnel furnace structure design, a seal-style tunnel electric oven was studied in which seal-style chain mesh belt return furnace structure was used to realize heat preservation of working and nonworking chain mesh belt, and reduce the heat-loss of non-working chain mesh belt. Through analysis on the force of scroll, the equation of critical effective tension was derived to determine the appropriate wrap angle. Based on the dynamic characteristic analysis of seal-style chain mesh belt return-furnace structure, the formula of limited dynamic tension was derived, and the necessary conditions of non-slip between chain mesh belt and scroll were achieved to ensure the steady transmission. Test results show that it is obviously better than the traditional open-style tunnel oven on energy saving effect.