Filed observation for water balance in upland red earth of Central Yunnan Plateau was made using self-made evapotranspiration-permeameter in 1983-1985.Data obtained showed that (1) the results obtained by the evapotranpiration-permeameter were quite consistent with the data of the Hydrologicalstation in the same period,with proved that the self-made evapotranspiration-permeameter is highly precise,Convenient for operation,(2) soil mulching study gave very good results for both iutrase soil water retention and crop yield.