The n-divided difference of the composite function h:= f o g of functions f, g at a group of nodes t0,t1, ···, tn is shown by the combinations of divided differences of f at the group of nodes g(t0),g(t1), ··· ,g(tm) and divided differences of g at several partial group of nodes t0,t1, ···, tn, where m = 1, 2, ···, n. Especially, when the given group of nodes are equal to each other completely, it will lead to Faa di Bruno's formula of higher derivatives of function h.