Abstract: Soil moisture evaporation plays an important role in the fields of surface water balance and the surface energy balance. Measurements of cumulative evaporation on soil moisture have been carried out in the laboratory using laser sensor. In this study, moisture content of clay loam and beach sandy soils were monitored using an unexpanded 5 mW Helium –Neon Laser ( = 0.63 m) incident through an optical fibre on one side of an equilateral triangular glass prism which was partly buried in the soil sample. The total internal reflected beam from the sample through the prism was collected from an output optical fibre into a detector and a multimeter. In order to dry and evaporate water from the soil, a 60 Watts incandescent light and a fan were placed above the soil sample container and made to operate simultaneously.