The film thickness distribution and average thickness outside a horizontal test tube were measured by using film-thickness meter.The effects of liquid load，evaporation boiling point，temperature difference and tube diameter on the film thickness，the waving intensity and，as a result，the heat-transfer film coefficients outside the horizontal-tube were determined experimentally.Experiments of the heat-transfer coefficient of horizontal-tube evaporation were conducted with various operation parameters.Equations of evaporation heat-transfer coefficient were set up by regression of experimental data.These results provide a basis for further developing high efficiency heat-transfer process and novel evaporators.