The viscosity composition temperature variation was investigated by measuring the kinematic viscosity of poly(α-olefins) (PAOs) and silicone oils and their blend oils with different blending ratio in the temperature range from -50℃ to 50℃.The experimental results show that the viscosity value of the blend oils is much less than the calculated value based on the international general viscosity model.When mixed with PAOs and silicone oils whose viscosity is much different,the high and low temperature viscosity of the blend oils varies between that of PAOs and silicone oils.When mixed with the base oils whose viscosity is similar,the low temperature viscosity of the blend oils is smaller than that of each single component in the certain ratio range.The blend oils show more excellent low temperature fluidity than each single component.The PAOs and silicone oils could be used as viscosity decreasing agent with each other at low temperature to further improve the low temperature property of lubricating oil.The intermolecular interaction was introduced to explain this phenomenon.