Abstarct: Increasing application of gas turbines in various fields of industry has drawn researchers' attention to the efficiency of these turbomachines. Efficiency of turbines can be enhanced through inlet flow temperature but it necessitates new methods for cooling and protection of turbine blades against thermal stresses. Therefore, this thesis has been devoted to the 3D simulation of fluid flow and heat transfer in turbulent and unsteady flow in order to investigate film cooling on the plate. In this research, oscillation frequency of the main and cooling flow in blowing ratio of 0.5, as an influential parameter in film cooling, has been investigated. Oscillation frequency of velocity was considered (180-2144) Hz for both main and cooling flow. Moreover, with considering two rows of injection holes with diameter of 0.025m, creating spanwise pitch and compound angle as effective geometric parameters on film cooling, different arrangements were developed and four geometries were considered for numerical assessment. Therefore, the focus of this research is appraisal of geometrical and flow parameters of film cooling on a plate. DES turbulent model has been employed in this simulation. According to the achievements, this model represents noticeable results in validation and simulation. The results indicated that applying of compound angle -45 to +45 for each row of holes in center line increases efficiency of cooling in the frequency of 1072 Hz through decline of heat transfer from main stream to the wall. By imposing spanwise pitch to 1.5D among the holes in each row, the highest average cooling efficiency in spanwise direction of the wall in frequency of 1072 Hz has been achieved. Keywords: Film cooling effectiveness, Blowing ratio, Oscillation frequency, Injection hole, Spanwise pitch, Compound angle Increasing application of gas turbines in various fields of industry has drawn researchers' attention to the efficiency of these turbomachines. Efficiency of turbines can be enhanced through inlet flow temperature but it necessitates new methods for cooling and protection of turbine blades against thermal stresses. Therefore, this thesis has been devoted to the 3D simulation of fluid flow and heat transfer in turbulent and unsteady flow in order to investigate film cooling on the plate. In this research, oscillation frequency of the main and cooling flow in blowing ratio of 0.5, as an influential parameter in film cooling, has been investigated. Oscillation frequency of velocity was considered (180-2144) Hz for both main and cooling flow. Moreover, with considering two rows of injection holes with diameter of 0.025m, creating spanwise pitch and compound angle as effective geometric parameters on film cooling, different arrangements were developed and four geometries were considered for numerical assessment. Therefore, the focus of this research is appraisal of geometrical and flow parameters of film cooling on a plate. DES turbulent model has been employed in this simulation. According to the achievements, this model represents noticeable results in validation and simulation. The results indicated that applying of compound angle -45 to +45 for each row of holes in center line increases efficiency of cooling in the frequency of 1072 Hz through decline of heat transfer from main stream to the wall. By imposing spanwise pitch to 1.5D among the holes in each row, the highest average cooling efficiency in spanwise direction of the wall in frequency of 1072 Hz has been achieved.