In this chapter, we will discuss the following key points: mechanical similarity, unit parameters, and specific speed of hydro turbine; efficiency conversion and unit parameter correction of hydro turbine; model test and comprehensive characteristic curves of turbine; performance and operation characteristic curves of turbine; selection of turbine types and parameters; and dimension determination of spiral case and draft tube. Students should be acquainted with the similarity law and the unit parameters of hydro turbine; master the efficiency conversion and unit parameter correction method; be familiar with the model test and characteristics of hydro turbine; master the selection method of turbine; be familiar with determining the dimensions and drawing profiles of spiral case and draft tube.