Trace element content of 1049 soil samples collected from Simao districtity Yunnan were determined.Results obtained showed that the total contents B and Cu in the soils of Simao are approximately the same as the mean contents in soils of the country,those of Mo,Zn,Mn are lower than the mean values of the country;available B,Mo,Zn are generally deficient,the samples of which the contents of B,Mo and.Zn are below critical values constitute 9l%,77%,and 52% respectively; availaible Cu and Mn are more abundant.Trace element conttnts in soils of Simao vary in a greater range,and they are distributed unevenly,being affected by genetic conditions such as parent materials,.climate relief etc.and genetic procPSS.177 field experiments in 58 sites showed significant of trace element fertilizers on crop yield increase with a the increase rate of 14.1%.