The introduction of nanometer-sized pores into low dielectric (k) materials is the most promising approach in producing ultra-low dielectric constant materials (k < 2.2). However, since the increased pores in low-k films lowered the mechanical strengths, it is important to optimize the mechanical properties by controlling the pore morphologies such as pore size, its size distribution and interconnectivity. We prepared nanoporous low-k films by using a chemically reactive cyclodextrin (TESCD) as a porogen to acquire chemical bonding with the low-k matrix, poly ( methyl trimethoxy silane-co-bistriethoxysilyl ethane). The porosity of nanoporous low-k films linearly increased with porogen loading, which indicated great compatibility between porogen and matrix, and its dielectric constant was as low as 2.2 (from 3.0) at 40% of porogen loading. Nanoindentor was applied on the nanoporous low-k films prepared by either TESCD or poly( caprolactone) porogen to measure elastic modulus and surface hardness. TESCD porogen resulted in much less reduction in elastic modulus and surface hardness from similar to 16GPa to similar to 7.3 and from similar to 2.7GPa to similar to 1.0 at 27% of porosity, respectively, while PCL porogen brought about the dramatic decrease in both mechanical properties at the corresponding porosity. This result may be due to the chemical bonding between TESCD and the matrix during its crosslinking reaction, which led pores.