Abstract: Abstract: In order to reveal the complex changing process of the liquid moisture content sequence at all depth levels of soil vertical section in seasonal frozen region covered with thick snow, based on the field experimental data measured during the winter from November 2013 to April 2014, we analyzed the variation characteristics of liquid moisture content of soil layer in the different depth levels of 5, 10, 15, 20, 40, 60, 100, 140 and 180 cm under the following treating conditions: bare land area (no snow cover), nature snow cover area, compressed snow cover area and thickened snow cover area. And the dispersion degree of time series was evaluated with some indices like coefficient of variation and variance. Then the preliminary identification of spatial distribution regularities on soil liquid moisture content complexity was made under different snow cover treating conditions, and at the same time, we identified and checked out the complexity of the sequence of soil moisture content by the method of wavelet transform information cost function. During the seasonal freezing and thawing period, the snow cover blocked the water vapor transmission and energy exchange process between soil and external environment, owing to its high albedo and low thermal conductivity, the infiltration of snowmelt water played a role in the migration of soil liquid moisture and the soil temperature at the parallel time. The biggest variation amplitude of soil liquid moisture content was 18.31%, which appeared at the depth of 20 cm soil layer under the condition of bare land treatment, while it appeared at the depth of 15 cm soil layer under the condition of nature snow cover area, at the depth of 15 cm under the condition of compressed snow cover area and at the depth of 10 cm under the condition of thickened snow cover area, which showed a trend of gradually rising in 4 different levels. The largest discrete degree appeared at the depth of 20 cm under the treatment condition of bare land; with the increase in snow cover thickness and the enlargement of snow density, the maximum level of the discrete degree of the series gradually moved upward, and the variation coefficients of the discrete degree level were 6.0189, 6.1367 and 6.8546 respectively, whose fluctuation grew stronger. Wavelet transform information index could measure the complexity of the soil moisture content of each soil layer, and complex active layers under the treatment condition of bare land, nature snow cover, compressed snow and thickened snow were 21, 18, 14 and 10 cm; the influenced area of environmental factors on soil was decreased, and the soil active layer moved upward the surface in the presence of snow. The study reveals the complexity characteristics of soil moisture migration during freezing and thawing period in cold region of North China, and it provides the important guiding significance for predicting soil moisture reasonably, and promoting water resource utilization precisely and efficiently in spring sowing time.