With Diphenylmethane diisocyanate(4,4，-MDI),2,2-(hydroxymethyl butyric acid(DMBA), poly(1,4-butylene adipate glycol) (PBA ,Mn=3000),1, 4 - butanediol（BG）and triethylamine(TEA), polyurethane dispersions(PUDs) was prepared by pelleting process. Results showed that the average particle sizes and particle size distribution of PUDs were mostly in the range of 59~215nm and 20~200nm respectively. The viscosities of PUDs were mostly less than 960mPa.s and increased with the increased of carboxyl content. The viscosity of PU acetone solutions were greater than 5000mPa.s and had trend of rise-fall with the increase of R value[R= n (-NCO)/n(-OH)]. TEM analysis showed spherical shapes of the particles with different sizes and multivariate distribution. The water absorption of the PUDs films were less than 2%.