Small hydropower has been considered as a solution to resolve the problem of exhaustion of fossil fuel and industrial pollution. In this study, we developed and tested a Cross-Flow Turbine with two guide vanes to optimize the small hydropower for the site condition with large fluctuation of head and flow rate. Furthermore, in the condition of constant inlet head, CFD analysis was carried out to analyze the effect of air suction and valve position on the performance characteristics. The results showed that the air suction can minimize the hydraulic loss caused by the Recirculation flow in the runner passage and flow impact on main shaft so that it can increase the turbine efficiency and output power.