The invention relates to a high-sensitivity and high-precision analysis method suitable for detection of organic sulfur compounds in cigarette mainstream smoke; the method adopts synthesized ionic liquid dispersion liquid-liquid micro-extraction of the organic sulfur compounds in the smoke, the volume of an extraction liquid is small, the extraction efficiency is high, and the sensitivity of the method is greatly improved; a sulfur-containing analysis protective agent is adopted; on the basis of an on-line gas generator, a target object is protected in real time, and the problems of peak shape trailing, inaccurate integration, poor signal response precision and the like caused by adsorption of a chromatographic system are remarkably solved. Compared with a traditional method, the method has the advantages that the consumption volume of the selected ionic liquid is small, the extraction efficiency is high, and the ionic liquid can be reused and is more economical, green and environment-friendly; the analysis protective agent is generated on line in real time, the protection range is wide, the defect that a conventional protective agent only protects part of target objects is overcome, the molecular weight of the protective agent is small, the protective agent cannot be deposited at a liner tube, a chromatographic column and an ion source, and the maintenance cost of a detection instrument is remarkably reduced.