vapor ation tests.A numerical simulation and in-situdrying test of granite residual soil in acertain weather condition of South China was carriedout.The results show that under thesame atmospheric condition， the filler with strong eerwater retaining ability needs longertime to reach the goal water content with the result of irregularity of water content.Amongthe factors affecting the drying of granite residual soil， the sensitivity levels range from thehighest to the lowest are the thickness of loose pave mi ent， sizeof soil's parameter， intensityof solar radiation， temperature and windspeed.Grannite residual soil filler with averaged i-ameterof2cm， the drying time can be reduced from5to2hifit's get ted ded.According toits diversity of filler water retaining ability， the timefor drying can be cutoff significantlyby particle diameter controlling and starting point of drying， to improve the efficiency ofsubgrade construction in raining areas of South China