  As nilpotent studies in knot theory, we focus on invariants of Milnor, Orr,
and Kontsevich. We show that the Orr invariant of degree $ k $ is equivalent to
the tree reduction of the Kontsevich invariant of degree $< 2k $. Furthermore,
we will see a close relation between the Orr invariant and the Milnor
invariant, and discuss a method of computing these invariants
