Abstract: In view of the actualities of Kendong 18 viscous crude oils transportation and the technology gap of theviscous oils transported by oil-in-water emulsion at home and abroad, a new technology of the oils transpor: ted by oil-in-water emulsion is presented based on systemic experimental investigation. The field tests are carried out successfully by a production pipeline with 24 km long and 259 mm interior diameter. The results show that (1) the total mean pressure drop along the pipeline is decreased from 1.39 MPa to 0. 563 MPa and the drag reduction rate is 59.7% while the concentration of emulsifying agent in the emulsion is 300 mg/L and the outlet temperature at the initial heating and pump station is from 48℃ to 55℃ and the fluid flowrate is from about 1100 m3/d to about 1200 m3/d, and the pipeline runs safely and steadily; (2) compared with the heating transpor tation technology, the running cost saves about 104×10⁴ RMB/a when the fluid flowrate at the initial pump station is about 1400 m³/d and the annual mean heating temperature for the fluid to flow through the two intermediate heating and pump stations is 20℃, which reflects mainly onthe obvious decrease of fuel gas and (3) the longer the distance of viscous oils transported by oil-in-water emulsion is, the more notable the drag reduction rate and the economic benefit are, which is not only feasible in technology, but also reasonable in economy, and its future application is bright.