Abstract: The film thickness distribution outside a horizontal test tube was measured with a film-thickness meter,to obtain the average thickness.The average film thickness increased with irrigation density of water.It was also relative to θ ,and the waving intensity was controlled by both irrigation density and tube radius.Dimensionless wave amplitude was defined and correlated in terms of Reynolds number and tube diameter,by regression of experimental data.Experiments of the evaporation heat-transfer coefficient on a horizontal-tube were conducted with various irrigation density,boiling point,temperature difference, heat flux and tube diameter.The influences of dimensionless film thickness and dimensionless wave amplitude on heat- transfer coefficients were obtained.These would provide a basis for further developing high efficiency heat- transfer process and evaporator.