Moisture migration in unsaturated loess considering temperature effect is studied by test. The test data show that the more is the temperature gradient in soil

and the less is the soil density

the more is the soil water content gradient resulting from moisture migration. If the soil primary water content is gradually added from very little value，the value of water content gradient resulted from temperature gradient first is lower，then bigger and finally lower. After analyzing the test data

taking the soil density and moisture content into account

the formula is obtained to determine the water content gradient resulting from the temperature gradient. The test and calculated data verify the reliability of the formula. And the method is got to determine the hydraulic head of unsaturated soil under thermal gradient

in which the temperature gradient

soil density

soil water content and water content gradient all are taken into account.