Abstract This paper analyzed three misunderstandings in teaching of insoluble electrolyte and put forward some suggestions. The three misunderstandings were:(1) the greater Ksp of the insoluble electrolyte, the greater solubility of it; (2) precipitation with high solubility could transform to precipitation with low solubility, but not vice versa; (3) precipitation with large Ksp could transform to precipitation with small Ksp, but not vice versa.