Orbital angular momentum (OAM) beam with helical phase distribution has demonstrated important ap-plications in information optics, optical trapping, and optical manipulation. In this paper, we designed a planar optical device which can generate a periodic array of focused orbital angular momentum beams. Based on detour phase encoding, the phase distribution calculated by fractional Talbot effect is implemented on this planar optical device. The property of this optical device with periodic square and hexagonal structures is simulated by finite difference time domain (FDTD) respectively. The optical device with explicit advantages of being easy to fabricate, splice, dup-licate, and integrate can efficiently prop up the generation of high-quality large-area array-type OAM beams.