Abstract: Variable speed operation can greatly improve the operation efficiency and regulation performance on hydropower unit. It is an effective way to solve the low operation efficiency and poor regulation quality on small hydropower unit. This paper discusses the variable speed operation schemes and control strategies for small hydropower units. The suitable system mathematical model and control strategy model are built for small hydropower units. The variable speed unit dynamic process of different control strategies is compared by simulation. The results show that, small hydropower unit is more suitable for using variable speed scheme based on full power converter and synchronous generator, at the same time, the control system control strategy suitable for the grid side converter control inverter DC bus voltage and reactive power output, the machine side converter control active power, the governor control speed of unit. The power anti-regulation phenomenon does not appear in simulation. And the active power stability time can be achieved in 0.9 seconds. The results of this paper can provide reference for the efficient development of small hydropower resources.