Hybrid orbital theory is an important part of the chemical bond theory. The bonding ability of hybrid orbitals and the angle between two hybrid orbitals are the most important and difficult topics in the teaching and learning of hybrid orbital theory. Most textbooks usually give the relevant formulas directly and ignore their derivation, which does not meet the needs for the advanced learning of some students. This paper provides a simple derivation of these formulas to dispel students' doubts and deepen their understanding of hybrid orbital theory.

Keywords： Hybrid orbital theory ; Maximum bonding capacity ; Angle between two hybrid orbitals