The understanding of size distribution and chemical composition of aerosol particles in human exhaled breath could provide helpful information for disease diagnosis，environmental exposure assessment，etc.In this study，the feasibility for simultaneously acquiring the size distribution and chemical composition of exhaled breath particles（EBPs） of human by single particle aerosol mass spectrometry（SPAMS） was preliminarily investigated.The EBPs were dried with a Nafion tubing，then directly analyzed by SPAMS.The number concentration of EBPs for a healthy adult is about 227-1 043 pcs/L，and the limit of detection（LOD） for obtaining a representative size distribution profile is 2 500 pieces，which means approximately 10 L of breath sample is required for the analysis.The exhaled particles sizes dominantly ranged from 200 nm to 1 000 nm，and the peak was observed at 460 nm.For the exhaled particles，the size distribution and chemical profiles reflect the information involving both exogenous and endogenous particles.Compared with that for particles in ambient air，the size distribution profile for exhaled particles contained higher abundance of relative particle numbers（RPNs） in the ranges of 200-300 nm and 440-660 nm，which were lower than or comparable with the RPNs in the ranges of 320-420 nm and 680-2 000 nm.Regarding the chemical composition，it was speculated that the higher presence of CxHyO+z（x=1~3，y=1~7，z=1~3），PO-3，CN- and CNO- in the exhaled particles（680-2 000 nm） might result from the endogenous phosphatidylglycerol and protein，whereas C-3、C-4、C+、C+3、C3H+and C+4in the range of 200-300 nm concern with the carbon of exogenous particles in the inhaled air.