Abstract Thermal expansion coefficients of yttria stabilized zirconia(YSZ) with the Y 2 O 3 content of 3, 6, 8 and 10 mol% were measured using a push-rod type dilatometer in the temperature range from 103 to 876 K. The thermal expansion coefficient of YSZ decreased with the increase of the Y 2 O 3 content. The thermal expansion coefficient of YSZ was theoretically estimated for the various Y 2 O 3 contents using the values of isochoric heat capacity, molar volume, isothermal bulk modulus and the Gruneisen constant in a good agreement with the experimental results. Among the physical properties, the bulk modulus is considered to be mainly responsible for decreasing the thermal expansion coefficient of YSZ with the increase of Y 2 O 3 content. The doping effect of Y 2 O 3 in YSZ on the thermal expansion coefficient was discussed using a molecular dynamics simulation.