Crop residue open burning is an important emission source of ambient particles in China.This study analyzed the particle emission characteristics of crop residue open burning through combustion experiments with a novel open combustion simulation device using three typical crop straws in north China(corn,wheat,and rice).Particle samples size rang-ing from 0.006-9.890 μm were collected by an Electrical Low Pressure Impactor plus,a high size-resolution instrument capable of dividing particles into 14 size stages.The size dis-tributions of organic carbon(OC),elemental carbon(EC),water-soluble ions,and elements were analyzed,and source chemical profiles were constructed for PM0.1,PM1,PM2.5,and PM10.The number concentration of particles was concentrated in the Aiken nuclei mode(0.006-0.054 μm),accounting for 75％of the total number,whereas the mass concentration was concentrated in the accumulation mode(0.054-0.949 μm),accounting for 85.43％of the mass loading.OC,EC,Cl-,and K(include total K and water-soluble K)were the major chem-ical components of the particles,whose mass percentage distributions differed from those of other components.These five main components exhibited a bell-shaped size distribution in the 0.006-9.890 μm range,whereas the other components exhibited a U-shaped distribu-tion.Among the chemical profiles for PM0.1-PM10,OC was the most important component at 10-30％,followed by EC at 2％-8％.The proportions of K+,Cl-,and K varied substantially in different experimental groups,ranging from 0-15％,and K+and Cl-were significantly correlated(r=0.878,α=0.000).