The orbital angular momentum of vortex beams can be used to realize micromanipulation of the particles.It can also encode the particles to realize free space optical communication.Because of its wide potential applications

the characteristics of vortex beams have become a hot topic in recent years.In this paper

the propagation characteristic of integer order double-vortex beam is studied.The propagation expression of double-vortex beam is derived by using ABCD optical matrix firstly.Then under the condition of same topological charges

the evolution of double-vortex beam spotwith transmission distanceis observed by MATLAB software.The simulation results show that the spotcharacteristics of double-vortex beam can be preserved after propagation without affecting the orbital angular.It shows that the double-vortex beam is stable in the process of transmission

which is suitable for free-space optical communication system.