Within the network, interorganizational dyadic ties are formed, adjusted and dissolved. We call it network change. The exist of network inertia has been the obstacle which blocks the organization to answer network change. This paper argued that organizational modularity capability determines its capability to overcome network inertia and it should develop its capability on product modularity firstly and then try to improve its capability on organization modularity to maximize the flexibility gained from interorganizational network. Taking scientific research institutions in military industry as case, we analysis network change and the modular recombination which they are located. We argued that the insufficiency on product modularity has limited the capability on organization modularity. Farther more, we describe that how modularity to help scientific research institutions overcome network inertia.