We propose and analyse a new model of thermocapillary convection with evaporation in a cavity subjected to horizontal temperature gradient.rather than the previously studied model without evaporation.The pure liquid layer with a top free surface in contact with its own vapour is considered in microgravity condition.The computing programme developed for simulating this model integrates the two-dimensional,time-dependent Navier-Stokes equationsand energy equation bya second-order accurate projection method.We focus on the coupling of evaporation and thermocapillary convection by investigating the influence of evaporation Biot number and Marangoni number on the interfacial mass and heat transfer.Thtee different regimes of the coupling mechanisms are found and explained from our numerical results.