In this study, low-dielectric constant (low-k) SiOC(H) films deposited using conventional plasma-enhanced chemical vapor deposition (PECVD) by varying flow rates of the deposition precursors were investigated through various characterization techniques. The deposition precursors were DEMS and ATRP, which acted as a network matrix and sacrificial porogen, respectively. Experimental results indicated that both DEMS and ATRT precursors influence the properties of resulting porous low-k SiOCH films. But matrix DEMS precursor causes greater impact. With an increase of DEMS flow rate, an enhanced cross-linking was formed, leading to a higher hardness, smaller pore size, better electric performance, and stronger dielectric breakdown strength. However, a higher dielectric constant (k) is the cost.  The k values of the porous low-k SiOCH films with various ATRP flow rates (1700~2500 sccm) remained unchanged, although, the optimized electrical characteristics and reliability were obtained as ATRP flow rate was 2100 sccm.