Volatile organic compounds (VOCs) are organic chemicals which can exist in the form of vapor at room temperature.Endogenous VOCs can be produced by different biochemical processes in the human body.They can be transfered to lung through bloodstream and released through breath.Many researches show that exhaled VOCs can be significantly changed when people suffering cancers or inflammation. Detecting exhaled VOCs through instrument with high sensitivity make it possible to detect cancers in early phase in a noninvasive and rapid way,which reduce the suffering of patients.In conclusion,exhaled VOCs detection is a promising method for early diagnosis of cancers.