MPLS VPN is an important technique for the implement of VPN, which is capable of overcoming some vital shortcomings of IP network and attracts wide attention. Combining the advantages of IPSec with those of MPLS, a security solution is put forward. MPLS VPN is modeled as a discrete event system. Then a simulation platform of MPLS VPN is built with C ＋ ＋The security solution is verified and the result shows that it is feasible.