In this article, we prove that a finite solvable group with character degree graph containing at least four vertices has Fitting height at most 4 if each derived subgraph of four vertices has total degree not more than 8. We also prove that if the vertex set ρ(G) of the character degree graph △(G) of a solvable group G is a disjoint union ρ(G) =π1∪π2, where |πi|≥2 and pi,qi∈πi for i = 1,2, and no vertex in πl is adjacent in △(G) to any vertex in π2 except for p1p2 and q1q2, then the Fitting height of G is at most 4.