We theoretically demonstrate the generation and detection of broadband multi-channel Orbital Angular Momentum(OAM) by a micrometer-scale meta-reflectarray. The meta-reflectarray composed of patterned silicon bars on a silver ground plane can be designed to realize phase modulation and work as chip-level OAM devices. Compared to traditional methods of OAM generation and detection, our approach shows superiorities of very compact structure size, broadband working wavelength (1250-1750 nm), high diffraction efficiency (~70%), simultaneously handling multiplex OAMs, and tunable reflection angle (0-45°). These fascinating advantages provides great potential applications in photonic integrated devices and systems for high-capacity and multi-channel OAM communication.