Abstract: Using the descriptive analysis,linear trend fitting and cumulative anomaly methods,the annual maximum depth of frozen soil,the average minimum air temperature and the average minimum ground temperature in each winter month（from October to the next February） at Tongliao National Basic Meteorological Observation Station during 1962-2011 were compared and analyzed.The results showed that the maximum depth of frozen soil at Tongliao Station for many years on the average reached 131.7 cm.And the maximum value appeared in February of 1977 and the minimum value appeared in February of 2007,and the maximum value was 1.4 times as the minimum.Under the background of the global climate warming,the maximum depth of frozen soil at Tongliao Station had obvious age change characteristics.At the terminal stage of 1960s-1970s,the maximum depth of frozen soil showed a gradual increasing trend.And the maximum depth of frozen soil showed a gradual decreasing trend after 1980s.At time scale of 50 years,the maximum depth of frozen soil at Tongliao Station had twice mutations,which occurred in the winter of 1971-1972 and 2005-2006.The maximum depth changes of the frozen soil at Tongliao Station showed significant negative correlations with the changes of the average minimum air temperature and minimum ground temperature.The lower the air temperature and ground temperature were,the thicker the layer of frozen soil was,and vice versa.The appearing time of the maximum depth of frozen soil was 1-2 months later than that of the minimum air temperature and ground temperature.