This study presents results from mechanistic experiments to examine the role of land properties in Indian summer monsoon within a regional climate modeling framework. The National Centers for Environmental Prediction (NCEP) regional spectral model (RSM) is nested by NCEP-National Center for Atmospheric Research (NCAR) reanalysis from May to July of 1996. The CNTL experiment uses realistic distribution of land surface properties with soil, vegetation, and orography. Following sensitivity experiments change an option from the CNTL experiment. The results have shown that the effect of orography is most important and land-sea contrast is second. Among of the effects of land surface characteristics, soil type has more important than vegetation fraction and vegetation type. From experiments of land surface characteristics, it is found that impact of evaporation changes alters precipitation pattern through not only local direct feedback effect but also remote dynamical effect. Land-sea contrast on the low level circulation affects only southwesterly flows at north of 10 N region, whereas orography affects whole inter-hemispheric gyre circulation. Removal of mountains strengthens the easterlies in southern hemisphere and weakens the westerlies in Arabian Sea and the Bay of Bengal region. It is found that orography plays a more important role in Indian summer monsoon than land-sea contrast. However, the basic pattern of monsoonal rainfall was maintained, which implies that the Indian summer monsoon is still largely dependent on the planetary-scale background flow.