This study aims to classify regions with different air pollution characteristics into groups in Taiwan, and further to evaluate and compare the air quality of various groups. A selected multivariate analysis technique, cluster analysis, is applied to the pollution monitoring dataset which including PM10, SO2, NO2, CO and O3. The obtained results have proved that the regions with similar air pollution characteristic can be appropriately grouped by applying cluster analysis. All 22 regions are classified into six groups, and the pollution pattern for each group is characterized as: Group 1 (high SO2/NO2; low PM10), Group 2 (high PM10), Group 3 (high SO2/PM10), Group 4 (low SO2/NO2/CO; high O3), Group 5 (low CO/NO2; high O3) and Group 6 (low PM10/SO2/NO2/O3/CO). Results from air quality evaluation indicate that the regions in group 6 (Ilan, Hualien and Taitung) have the best air quality while the regions in group 3 (Kaohsiung and Kaohsiung City) have the worst air quality in Taiwan. The results from correlation analysis reveal that incidence of the respiratory system disease is significantly positively correlated with pollution of NO2 and CO at 99% confidence level.