The process of LNG rolling evolution was simulated after stratification according to control equation of the process of rolling in LNG spherical tank, based on VOF model and boussinesq. Numerical analysis of the affecting factors for the roll. Research shows that the root cause of rolling for LNG is layering. The average convection velocity increased in the tank is followed with increasing of the quantity of environment heat leakage, accelerated the roll time of LNG. LNG rolling time could be lag because of large differences density in layered area but natural convection is severe within the layer. Roll will get the evaporation rate gather in the lower then caused the pressure augment and serious harm in the tank in a moment. Finally, some suggestions to prevent rolling were given. Providing theoretical guidance for LNG safety storage and optimize operations.