Abstract: As the development of environmental control technologies in poultry houses, a mixed ventilation by using the air inlets in the sidewalls and the exhaust fans installed in the gable-walls was created and has been applied in large-scale broiler buildings during the seasonal transition periods. In this article, field measurements were conducted in a broiler house with mixed ventilation, and the parameters of air exchange rate, air velocity, indoor and outdoor temperatures as well as ammonia concentration were experimentally studied. The results indicate the air exchange rate is sufficient in this building. Air velocities and indoor temperatures inside this building are appropriate and their distributions are uniform; furthermore, inside ammonia concentration can be controlled at a low level. This paper suggests that a broiler building applied with a mixed ventilation system can provide the birds with a good growing environment.