A chaotic mesh network system composed of four mutually coupled semiconductor lasers (SLs) is presented in this paper. For this system, the dynamical behaviors of each SL, the synchronization characteristics between arbitrary two SLs and the influence of parameter mismatches on the synchronization are investigated numerically, and the secure communication performance of such a system is analyzed. The theoretical simulation results show that all outputs from SLs in this mesh network system can route into chaos under suitable coupling condition, and global synchronization or partial synchronization can be observed for these four SLs. Based on chaos synchronization in this system, the bidirectional secure communication among multi-users can be achieved.