Abstract: Based on the basic equations of moisture migration in unsaturated soil， the twodimensional infiltration model of unsaturated soil that uses volumetric water content as control variable was proposed， and is programmed. The program could take the horizontal and vertical infiltration and infiltration capacity in the process rainfall into account. The numerical model for stability analysis of unsaturated soil slope that considering the changes of volumetric water content was constructed， in which the instantaneous moisture was timely imported in order to achieve realtime analysis of slope stability， and to search for the most dangerous slip surface. The engineering applications show that slope stability are closely related with volumetric water content， influence of initial moisture content is the greatest and the rainfall intensity is smaller. With the increase in the time of rain， the moisture content decreases from shallow to deep gradually while the most dangerous slip surface move gradually to shallow.

Key words: twodimensional rainfall infiltration, unsaturated soil slope, transient moisture content, stability analysis, programming