Abstract: When space undergoes rotation, both the projection of the spin operator along a certain direction and its eigenstate undergo transformation, but the transformed spin state should still be the eigenstate of the corresponding operator after transformation. This article uses this principle to discuss the transformation of spin state caused by spatial rotation, and obtains a transformation formula similar to the orbital wave function. Finally, the transformation formula of general angular momentum caused by spatial rotation is discussed.

Key words: spin, spin operator, spin state, spatial rotation