The surface evaporation of the extended meniscus liquid film in the microchannel driven by capillary force is the key process in heat sink and thermal management equipment.The physico-mathematical model was established by considering the variation of the apparent contact angle to describe the configuration of the total extended thin film region，including the equilibrium region，the interline region and the meniscus region.In addition，the ratio of disjoining pressure and capillary pressure was introduced to distinguish the film ranges of the different regions by considering the influence of film configuration，liquid property and channel size.The results indicated that the range of the interline region was quite small in the total extended meniscus region，nevertheless the variation of its surface temperature was much obvious，implying that the resulted Marangoni effect could cause great “pump” force to drive the film flow，which may be the main contribution of the interline region to the total extended thin film evaporation.The variation of evaporating rate，and also the resulted mean velocity of liquid film in the thin film interline region were revealed，which showed that there existed a local maximum value of evaporating rate in this region by the coupled influences of decreased film thickness and adhesion force caused by the disjoining pressure.