Larix gmelinii forest area is the largest of coniferous forests in north China, is an important carbon sink of China, and has important influence on Chinese sequstration and the global climate change. Because of its highly humid, cold and frozen environment, the dynamics of absorption and release of soil CH_4 in Larix gmelinii forest is different from others. Therefore, the research on soil CH_4 dynamics and its relationship with environment has an important theoretical and practical significance to reveal the local forest carbon dynamics and its effect on climate change. Study sites were selected in different slope positions of four kinds of typical Larix gmelinii forest communities in Inner Mongolia Genhe national ecological research station and done in May to September of 2011. The CH_4 were collected by static box and analyzed by an automatic cavity ring-down spectrophotometer, and measured the soil temperature of different depth and soil moisture content as well, Using variance, correlation analysis and other statistical methods, we studied the monthly changes of soil CH_4 fluxes, and analyzed the effect of soil temperature and moisture content on CH_4 fluxes. Results showed as follow: (1) Soil CH_4 in hilltop emitted in spring, uptook in summer, and released again in autumn in hilltop. Uptaking was greater than emission, the average flux of top slope is -68.12 mug·m~(-2)·h~(-1). (2) Soil CH_4 in upper part of slope uptook in spring, summer and autumn, the average flux of upper part of slope is -342.49 mug·m~(-2)·h~(-1), (3) Soil CH_4 in lower part of slope emitted in spring, uptook in summer, emitted again in autumn, emission is greater than absorption, the average flux of lower part of slope is 67.8 mug·m~(-2)·h~(-1). (4) Soil CH_4 in bottom of hill emitted in spring, summer and autumn, the average flux of the bottom of slope is 263 mug·m~(-2)·h~(-1). On the whole, the result of soil CH_4 fluxes of Larix gmelinii was absorption is greater than emission, this shows that Greater Higgnan Mountains which located in cold temperate zone is the sink of CH_4. CH_4 fluxes has certain correlation with temperature and soil moisture content at all times during the observation, these two factors affect the change of CH_4 fluxes from different aspects, and with the change of slope positions, soil environmental conditions changed as well, this is also an important factor affecting CH_4 fluxes.