Abstract: Abstract: Ammonia and carbon dioxide emissions from animal houses have been one of the major environmental protection concerns, because they may raise environmental problems and pose hazards to public health. There has a vast territory and diverse climate types in China, which can be divided into five thermal zones. The environmental control systems in different climatic regions vary according to the type of pig house construction. Typical seasonal emissions in different climate zones should be measured to provide data support for Chinese total ammonia and carbon dioxide emissions. In order to enrich the database of ammonia and carbon dioxide emissions from pig houses in cold climate zones, two mechanically ventilated large-scale gestation sow houses were selected to calculate ammonia and carbon dioxide emission rates. One single-floor gestation sow house locates in Hebei Province and is full of Chinese indigenous pigs, the other multi-floor gestation sow house locates in Beijing and is filled with introduced pigs. They were mechanically ventilated and automatically fed. The manure management systems in the two pig houses were “pull-plug” system and “solid-liquid separation” system, respectively. The ammonia and carbon dioxide emission rates of the two experimental pig houses were calculated by monitoring the ventilation rates and the concentration of ammonia and carbon dioxide at the exhaust outlets. Because of the double impacts of Asian fever and corona virus, the data were obtained only in summer in the multi-floor pig house. And the emission rates were monitored both in summer and winter in the single-floor pig house. The results showed that the average daily emission rates of ammonia in the single-floor pig house (winter and summer) and in the summer of the multi-floor pig house (before and after the scrubber) were (17.4±5.3), (65.8±4.8), (150.9±8.6) and (84.6±6.8) mg/kg, respectively. The average daily emission rates of carbon dioxide were (8.9±0.8), (18.1±3.1), (11.7±1.8) and (15.7±1.9) g/kg, respectively. The emission rates of ammonia and carbon dioxide were higher in summer. The trends of daily ammonia emissions from pig houses with different manure managements were different, and the average daily ammonia emissions from the piggery with “pull-plug” system fluctuated in a manure discharge cycle. The variations in ammonia emissions showed probably more within a day than between days in the piggery with the “solid-liquid separation” system. There was a double hump trend before and after the scrubber (R2=0.95), and the peak interval was consistent with the daily manure removing interval. In winter and summer, the carbon dioxide emission rates both showed a diurnal variation. The peak interval was consistent with the feeding time of pigs, and the fluctuation of night emission rates was small. The carbon dioxide emission rates after the scrubber were higher than those before the scrubber (R2=0.92). The age of sows was positively correlated with the daily average carbon dioxide emission rates. It was found that in the mechanically ventilated pig houses with constant ventilation rate, the ammonia emission rates were affected by the mode of the manure management, feeding patterns, and pig activities. This study provided basic data support for the ammonia and carbon dioxide emissions of large-scale single-floor and multi-floor gestation sow houses in cold climate zone.