Abstract: A method for determination of the 4 methyl cyclosiloxanes in electronic and electrical products by gas chromatography-mass spectrometry was established. The crushed sample powder of 1 g was extracted by ultrasonic at 30℃ for 30 min with 10 mL of tetrahydrofuran. The extracting solution was filtered by 0.22 μm organic filter membrane, the 4 methyl cyclosiloxanes of which were determined by GC-MS. As shown by the results, linear relationships between mass concentration of 4 methyl cyclosiloxanes and their peak area were kept in the range of 0.1-10.0 mg·L^-1, with detection limits (3S/N) in the range of 1.86×10^-3-7.02×10^-2mg·kg^-1. Recovery test was made on negative samples at 3 concentration levels by standard addition method, giving results in the range of 85.7%-106%, and RSDs (n=7) of the determined values were less than 5.0%.