Adaptation is an effective way to reduce the mesh dependence of finite element computation result. On the basis of the p-version finite element method, the adaptive analysis method for three dimensional unsteadytemperature field is established. The adaptive policy is element order raising method. The error estimate selects the high-order temperature as the best estimate of precise value. According to a three dimensional concrete plate sample, the influence of some factors on calculation error and element order is researched, including the adiabatic temperature rise, heat transfer coefficient, model dimension, time step length and boundary temperature difference. The results show following conclusions. The adiabatic temperature influences calculation error more than heat transfer coefficient when the boundary temperature difference is low. The calculation error in small size model is less than in large size model when in higher order computation. The calculation time step length variation reflects the time gradient of temperature field, and the longer time step length demands higher order. The temperature difference variation of model boundary shows the space gradient of temperature field, and the larger boundary temperature difference requires higher order.