Abstract: The regularity of the formation,development and disappearance of air pressure in the soil unsaturated zone for rainfall infiltration,and also its influence on the infiltration flow were investigated by the special experimental system.Meanwhile,combining with formation analysis the conditions forming air pressure were approached,and the relationship between air pressure,total potential of soil moisture and groundwater table was also examined and explained.When the groundwater table is more shallow (<2m),the experimental results show that the total ponded infiltration water affected by air pressure will reduced by one-third.