Abstract: Temperature interference of crustal tilt observation may be divided into two parts, heat tilt due to the sun shine and effect of the room temperature variation.In this paper, the analytical expressions for heat tilt are derived from the heat expension principle.beat tilt in surface layer is related to the slope of geography besides the amplitude of temperature variation of the ground, physical properties of rock and thickness of hole.But when thickness exceeds 30 meters, the annual amplitude of the heat tilt must be less than 0.02 second, although the slope of the geography is big.we take Zhangjiakou station as an example to show that room temperature variation is an important interference for tiltmeter inside the hole.Tilt quantities of the tiltmeter itself and instrument pier caused by short-period room tempcrature variation are estimated.