In the face of the rapid and drastic development in recent times, we should deepen our cognition and try to find a way to foresee things. Besides external relation and internal relation, there is an important relation from the perspective of Systemology, namely inter-part relation. The proposition of inter-part relation will contribute to getting a deeper understanding of sustainable things and seeing through the origin and the ultimate destination clearly. We can resolve connected problems and group contradictions by the chain of methods.