Solar cavity receiver plays a dominant role in the light-heat conversion process of the solar power system. Its performance can directly affect the efficiency of the whole power generation system. The start-up thermal performance of a saturated steam solar cavity receiver with absorber tubes was numerically studied. A six-side prism with inclined top and bottom faces was chosen as the solar cavity. During the start-up of the receiver, the temperature rising rate was considered as the main control condition, and different values were selected from different temperature regions. Three kinds of start-up processes were simulated. According to the temperature rising rate and the evaporation rate, rising curves of water temperature, pressure and evaporation were designed, and the net energy required by the receiver during start-up was calculated. The results demonstrate the proportional relationship between the net energy and the evaporation rate. A computational model established for the start-up process was used to calculate the energy required by the aperture from heliostats during the whole start-up process. Thermal efficiency of the receiver has been gained as well, which is very low during the early start-up period due to severe convective heat loss. The velocity of air around the cavity can hardly be affected during start-up process, but the temperature of air changes a lot with the start-up time. (C) 2012 Elsevier Ltd. All rights reserved.