Abstract: This study aimed to investigate the moisture loss rules of gramineous forage, leguminous forage and forage crop during natural drying process. The fresh weight of different varieties of forage was immediately determined after cutting （0 day weight）; subsequently, the forage samples were dried to constant weight in oven at 75 ℃ for 24 h （dried weight ）; the forage samples were wilted in air and their weight were determined and recorded at the 0.5, 1.0^st , 2.0^nd , 3.0^th , 4.0^th , 5.0^th , 6.0^th day after cutting, respectively; the moisture content of different varieties of forage at different time after cutting was calculated by a formula. The results showed that the moisture content changing of gramineous forage, leguminous forage and forage crop during natural drying process exhibited a similar tendency： with the extension of drying time, the moisture content of different varieties of forage was generally decreased; in the initial stage after cutting （from 0 to 1^st day）, the moisture content was dramatically decreased, and in the later stage after cutting （from 2^nd to 4^th day and from 5^th to 6^th day） , the moisture content was slightly decreased. The results obtained in this study provide references for the scientific preparation of high quality hay.