Abstract: In this paper, a parallel communication algorithm of supersonic chemical oxygen iodine laser (COIL)’s calculation using multiblock structured mesh has been designed and implemented. This communication algorithm that is designed for large scale supersonic chemical oxygen iodine laser’s simulation is based on JASMIN(J parallel adaptive structured mesh applications infrastructure) infrastructure. There are several communication problems in the large scale supersonic chemical oxygen iodine laser’s simulation such as the complexity of blocks’ connecting relationship description, the complexity of management of boundary conditions and the nonuniform of communication schedule. The communication algorithm in this paper includes a blocks’ relationship recognition algorithm to compute blocks’ connecting relationship automatically, a special data structure to help managing boundary conditions and a unified communication schedule which can reduce communication time. According to our calculation results, the communication problems can be resolved by the communication algorithm in this paper and supersonic chemical oxygen iodine laser based on this communication algorithm can be realized easily and simulated regularly. The simulation with 4.5 million mesh cells in this paper can run efficiently on thousands of processor cores.