Among the unintentional persistent organic pollutants (UPOPs), polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDDs/PCDFs) were measured from a stack of 28 small-scale waste incinerators (SWIs) from 2013 to 2015. The emissions of PCDDs/PCDFs ranged from N.D. to 208.3 ng-TEQ/Sm3 with an average of 21.1 ng-TEQ/Sm3 based on the International Toxicity Equivalency Factor (I-TEF). The 28 stack gas samples were categorized into four types and evaluated by the score plot of principal component analysis (PCA). Furthermore, 17 PCDD/PCDF congeners were divided with the number of chlorine substitutions by a loading plot. The correlations between PCDDs and PCDFs were also estimated. The emissions of PCDDs/PCDFs from 19 SWIs were below the emission standards, while nine SWIs significantly exceeded them in this study.