Abstract: Abstract: Broiler breeding will produce many pollutant gases such as ammonia (NH3). Acquiring the information of the orderliness and rates of NH3 emissions accurately during the broiler breeding is the foundation to estimate NH3 emissions. It can provide the theoretical support for the study of the mitigation and control of NH3 emissions during the broiler breeding. The broiler houses mostly use natural ventilation in China, the air flow field is complex and changeable, and it is difficult to measure and calculate the NH3 emissions accurately. Compared with the site test, breeding chamber test is more convenient and easier to control the environment variation. The purpose of this work was to study the NH3 emissions in simulated environment. In this study, a detection device was designed, which was used for broiler weight, waste, feed intake, water consumption and NH3 emission detection, and composed of broiler breeding chamber, gas sampling devices and parallel-connected gas detection instruments. The investigation to the sealing property of the chamber and the accuracy of the detection system, and the determination of the NH3 in the broiler breeding chamber were conducted. All of NH3 data were recorded automatically. In static test, standard gas concentration of 7.59, 22.77 and 37.95 mg/m3 were injected in the chamber, respectively. The results indicated that the average change rate of NH3 concentration was -4.40% in the chamber after 24 h, which meant that the breeding chamber sealing was good. The dynamic test showed the detection device had a stable performance. The NH3 of mass concentration of 37.95 mg/m3 passed through the broiler breeding chamber detection system in 6 h, the maximum and minimum mass concentration of NH3 measured were 36.75 and 35.22 mg/m3, respectively. The average concentration was 35.65 mg/m3 and the accuracy reached 93.94%. It meant that we could determinate the concentration of the standard gases in the chamber by using the detection system. We also carried out the short-term test of broiler breeding using the detection device. Through the measurement of the gaseous contaminant in the broiler chamber, the result showed that the concentration of NH3 in the dark period (10 p.m. to next day 6 a.m.) was greater than that in the light period (6 a.m. to 10 p.m.) in the breeding stage. The correlation between the broiler excretion amount and the NH3 concentration was positive at the early stage of the test, but it became negative in the later stge. What was more, the concentration of NH3 increased sharply on the 4th day after the manure was accumulated. The NH3 concentration test of broiler in short-term breeding reveals that the detection system has a good sealing performance, stability and detection accuracy. The detection system provides a facility for studying the relationship between the process of broiler breeding and the characteristics of NH3 emissions. Further research is needed to coordinate the ventilation quantity with the breeding quantity and fecal cleaning management.