  The classic Mckay correspondence gives a connection between finite subgroups
of $\operatorname{SU}(2)$ and the simply-laced Dynkin diagrams. In this
article, a direct proof is presented. The bipartite structure of the Mckay
diagrams is introduced. After that, the similar method can be used on finite
subgroups of $\operatorname{SO}(4)$, we get a edges-coloured graph. We finally
get some applications.
