The invention discloses a method for detecting various pesticide residues in tobacco by utilizing a multiwalled carbon nanotube. The method is characterized in that an organic solvent is used for extraction; the multiwalled carbon nanotube is used as a reverse solid phase dispersion adsorbent; the tobacco samples are purified through vortex and centrifugation; a high performance liquid chromatography-tandem mass spectrum coupled technology and a gas chromatography-tandem mass spectrum coupled technology are combined to realize the synchronous detection of various pesticide residues in the tobacco. According to the method, the multiwalled carbon nanotube is used as the reverse solid phase dispersion adsorbent, so that the purification effect, the influence on the adsorption of the target analyte due to the frequently-used polar adsorbents is eliminated while the matrix effects are reduced, and a cleaner solution is provided to decrease the maintenance of the instrument in the using process; the multiwalled carbon nanotube is low in preparation cost and less in dosage and has the effect of greatly reducing the experimental cost; the method provided by the invention has the advantages of being correct in measurement, high in sensitivity and good in repeatability, and has the effect of satisfying the requirement for rapidly analyzing and detecting the large batch samples.