Cloud simulation is important for creating images of out-door scenes. However, the complexity of this natural phe-nomenon makes the simulation of large-scale clouds difficult in real time. In this paper, we present a new method for 3D cloud simulation in which cloud animation is simplified and simulated by approximating Lennard-Jones Potential. To solve the N-body problem in Lennard-Jones Potential, we minimized the interaction between particles by divid-ing the simulation space into many cells and we defined a cutoff distance to perform calculation between neighboring particles. Additionally, a separate distance is introduced between particles to maintain the stability in the Lennard-Jones system. Our experimental results demonstrate that our method is computationally inexpensive and suitable for real time applications where large-scale simulation of clouds is required. © 2016 ACM.