Abstract: Carboxylic waterborne polyurethanes with different particle size and particle size distribution were prepared by two kinds of emulsification with isophorone diisocyanate(IPDI),poly(1,6-hexanediol/neopentyl glycol-alt-adipic acid) (PHNA),1,4-butanediol (BDO) and dimethylol propionic acid (DMPA) as the hydrophilic chain extending agent. The particle size and particle size distribution were measured by dynamic laser scattering method,and the stability,water absorption,tensile strength,elongation at break and gloss were determined successively. Results show that,the particle size range is from 40 nm to 340 nm,the particle size distribution (PDI) range is from 0.07 to 0.26,and different DMPA content and emulsification can lead to different partical size and PDI;among the WPUs,the highest tensile strength is 49.62 MPa with a 922% elongation at break,the least water absorption is 5.25%,and the top gloss is 87.8°;the partical size and PDI have an important influence on water absorption,tensile strength and gloss,but little on the elongation at break.