Study on existing indoor thermal environment is becoming more and more important for design of theindoor thermal environment and the application of energy-saving technology. In this work the fieldmeasurement of thermal environment in a complex atrium building was conducted and different effectson the indoor thermal environment were analyzed. The atrium is 14m in height. The first floor is forexhibition, and the cooling air can be supplied by air jets located on the upper position of the sidewall.The corridors on the second and third floors are not air conditioned. That is, a stratified air-conditioningsystem was used in the atrium. The field measurements were carried out in summer from July toAugust in 2006. The major field measurements included thermal environment parameters, such asoutdoor environment, indoor thermal environment of working zone in the exhibition region and verticaltemperature distributions in the atrium. The results show that the maximum temperature differencebetween the top and the bottom of the atrium reached up to 13C. The horizontal temperaturedistribution in the exhibition region was uniform, of which the largest deviation was less than 1C. Mostof the cases could meet comfort requirements of |PMV| < 0.5 and ADPI > 80%. The corridortemperature on the second floor was 5.9C higher than that on the first floor. And the temperature onthe third floor is 3C higher than that on the second floor. The vertical temperature distribution in theatrium could be significantly affected by the outdoor temperature. With shading on the dormer of theatrium, the temperature in the air-conditioned area of the atrium can reduce 0.8C. The measurementresults also show that the indoor thermal environment of the atrium could be improved by ventilationthrough upper openings, if the outdoor air temperature is lower than the inner temperature.