Abstract: A series of rosin pentaerythritol ester polyoxylethylene ether (RPEO) with different polymerization degree (n) of epoxy ethane (EO) were synthesized. Surface physicochemical properties of these products were measured. The results showed that surface tension (δ) varied from 34.4×10-5 to 40.5×10-5 (N/cm), critical micelle concentration (CMC) from 26-65(mmoL/L), lime soap dispersing power (LSDP) from 4.2% to 17.5%, emulsifying power (EP, with turpentine) from 58 s to 184 s, cloud point from 38℃ to 75℃. The (relations) between surface physicochemical properties of the products and polymerization degree of EO were first studied systematically. With the increase of n of EO, the surface activity was increased firstly, then towards stable or dropped a little, the application properties, such as EP, CP and LSDP, were improved with increasing of n, and reached balance where n equaled to 10.