Abstract: Base on observed soil moisture data during 1987 and 1996 in Tiebujia animal husbandry meteorological experimental station,the relationship of soil moisture contents with the changes of seasons,soil depths and rainfall was analyzed.The forecast models of soil moisture content at different soil depths were established.The results showed that the soil moisture content during the spring defrost time mainly depended on the soil moisture storage before frozen in the last year and the balance of frozen and defrost process.The average soil moisture content during forage grass germination period was significantly related to the rainfall and to the rainfall in the last or before last year as well.It was same as by the annual soil moisture contents.The soil moisture content reached at a relative high level in 4070 cm depths.The soil moisture did not meet the needs of the growth and development of the forage grass in the Qinghai Lake Region.

Key words: Soil moisture content, Soil moisture content, Forecast equation, Rainfall, Qinghai Lake Region, Natural grassland