Indium doped ZnS (ZnS:In) films were prepared on glass substrate using thermal evaporation technol- ogy. It was found that the structural, optical and electrical properties of ZnS:ln films strongly depend on the substrate temperature (Ts). By X-ray diffraction (XRD), atomic force microscopy (AFM), transmittance spectroscopy, and electric performance measurements, the effect of Ts on ZnS:In film is studied in detail. It reveals that Ts has impor- tant effect on ZnS grain size, crystallinity, lattice disorder, etc., which further leads to the obvious influence on its optical and electrical performance. Under the optimized Ts, the performance, especially the conductivity, achieved in this work is far higher than that reported for other n-type ZnS films.