Abstract: The 0.3 mm commercial grain-oriented silicon steel sheets were rolled further under 0.1 mm in gauge by conventional rolling (CR) and cross shear rolling (CSR) separately, then the finished strips were annealed in furnace in different atmospheres for tertiary recrystallization. Effects of heat treatment parameters, such as annealing temperature, atmosphere, holding time and heating rate, on the magnetic properties and tertiary recrystallization behavior of the ultra-thin grain-oriented silicon steel strips were investigated. The results show that the magnetic properties achieved in vacuum are better than those in hydrogen atmosphere with other technological parameters kept the same, and the magnetic properties become higher with improved structure after tertiary recrystallization under conditions of higher annealing temperature, longer holding time, and higher heating rate.