The work aims to qualitatively and quantitatively analyze semi-volatile pollutants in 25 different sources of recycled high-density polyethylene (rHDPE), so as to explore potential hazardous substances in rHDPE. Semi-volatile organic compounds were extracted using dichloromethane, and then qualitatively analyzed by gas chromatography-mass spectrometry in combination with NIST20 mass spectral library and retention indices. Semi-quantification was done based on reference standards selected according to structural similarity calculated by molecular descriptors and random forest algorithm. A total of 114 substances were detected in these 25 samples, with each sample containing 42 to 89 substances, with median concentrations ranging from 34 to 97 mg/kg. Common substances included alkenes typical in polyolefins, antioxidants, lubricants, and their transformation products. Among the high-concern substances, diisobutyl phthalate and nonylphenol were detected in over 50% of samples, with average concentrations exceeding 8 mg/kg. Although 1-tetradecene was not classified as a high-concern substance, its specific migration limit is only 0.05 mg/kg, while its average concentrat is 59 mg/kg, posing a potential migration risk. These results indicate that there are certain high-concern contaminants present in rHDPE fragments, which may pose potential risks to food safety when used as recycled packaging materials.