Abstract: In order to evaluate the effect of different types of pig houses in different seasons in Shandong Province, the present study was conducted to investigate the microclimate of pig house in spring, summer and winter. The air temperature, relative humidity, air speed, light intensity, ammonia concentration and quantity of bacteria in air were measured. The results showed the air temperature in semi-open pig house could be increased significantly (P＜0.01) (5.3℃ vs 2.2℃) when it was covered with plastic film in winter, but the air temperature was still lower than that in closing pig houses (P＜0.01). In summer, the air speed in semi-open pig houses was lower than outside, but the air temperature was adverse (P＜0.01). The closed pig houses with a ceiling had better ability of heat insulation, a higher air temperature in winter and lower temperature in summer than those in the house without ceilings. The air speed in closing or semi-open pig houses was both low in all the seasons (usually less than 0.26 m/s), and the light intensity in the pig houses was uneven. The quantity of bacteria in air and ammonia concentration in pig houses did not showed a coinciding rule. The higher concentration of ammonia was observed in winter and spring. However, higher quantity of bacteria in air was observed in summer.