The soil cannot be totally covered by plastic mulch in the field.And normally in the mulch holes should be preset for plants to emerge after sowing, and irrigation holes added for irrigation.The term of aperture ratio is often used to represent the above issue.So far very few national or international papers about evaporation from soil under perforated plastic mulch have been reported.In order to study characteristics of evaporation from the soil with initial homogeneous soil water content, a laboratory system of evaporation has been set up.Based on the dynamic observations of soil water and soil temperature, their variation regularities during evaporation and at the end of the evaporation were described, and calculations and analyses of soil temperature variation and soil water content distribution, functions of cumulative evaporation, relatively evaporation and cumulat ive evaporation per unit area of the film holes to aperture ratios performed.The results showed that under the influence of evaporation, the cumulative evaporation varied linearly with the square of the evaporation time, which corresponded to the bare soil evaporation theory presented by Gardner.These results have extended Gardner equation and expanded its application ranges, thus being very useful for further study on water and heat transport in plastic mulched field.