Cross-flow hydraulic turbine becomes viable in low head and small water flow rate. Because of its simple in structure and ease of manufacturing, it is familiar in scheme of small hydro-power in the site of the power plant. In order to obtain a cross-flow turbine with maximum efficiency, appropriate turbine design must be performed. Therefore here proper turbine design was done employing the all turbine parameters and computational fluid dynamic simulation was carried out as important tool for performance study of the turbine. The required turbine model was designed and computational fluid dynamics simulations was performed by using the commercial software ANSYS CFX v.12. After the high efficiency turbine was designed, computational fluid dynamics was conducted in order to validate the obtained solution. With attack angle of 180, maximum efficiency was found to be 82.52% constant for different values of head and water flow rate. Where as in CFD simulation case, maximum efficiency became 79% with fully opened guide vane. Guide vane was set at position where the water is discharge through the runner fully. In this paper all design parameters of cross-flow turbine were calculated at maximum efficiency and simulation was done by opening turbine gate value at different stages.