This study measured 71 volatile organic compounds (VOCs) collected using stainless steel canisters at 15 monitoring sites in two main Kaohsiung municipal sewers, A-Sewer and B-Sewer, during winter and summer periods in 2008 and 2009. The results indicate that the overall average of total VOCs, TVOC, in A-Sewer was 1173.51 ± 187.69 μg/m3, which was about 40% higher than that in B-Sewer (689.22 ± 151.64 μg/m3). However, TVOC in the winter/dry season was about three (or five) times that in the summer/wet season for A-Sewer (or B-Sewer). For the A-Sewer, chlorinated organics, aromatics, and alkanes were predominant, and altogether contributed to about 90.0% of the TVOC in winter and about 70.6% in summer, with alkenes, ethers, ketones, and sulfur compounds as minor components. For B-sewer, aromatics, alkanes, and chlorinated organics were predominant, and altogether contributed to about 94.1% of the TVOC in winter and about 74.3% in summer, while others were minor ones. The principal component analysis (PCA) and absolute component scores (APCS) models indicate that the percentage source contributions for A-Sewer were solvent usage (31.65 ± 11.27%), oil refineries and storage leaks (28.71 ± 11.52%), auto paintings (19.14 ± 9.74%), asphalt plants (17.05 ± 8.73%), and others (3.45 ± 3.95%). The percentage source contributions for B-Sewer were printing factories (45.35 ± 9.19%), oil refineries and storage leaks (31.78 ± 8.59%), solvent usage (18.64 ± 8.50%), and dry cleaning (4.23 ± 4.70%).