The mechanism of superstability of nanobubbles in liquid confirmed by many experimental studies is still in debate since the classical diffusion predicts their lifetime on the order of a few microseconds. In this work, we study the requirement for bulk nanobubbles to be stable by using molecular dynamics simulations. Periodic cubic cells with different cell sizes and different initial radii are treated to simulate the nanobubble cluster, providing the equilibrium bubble radius and the interbubble distance. We find out that for nanobubble with a certain radius R to be stable, the interbubble distance should be smaller than the maximum interbubble distance L* being proportional to R-4/3. (C) 2019 Elsevier B.V. All rights reserved.