Programmable RNA functional parts can serve as useful components in reengineering genetic circuits.Here, we report a design of programmable translational activator composed of a RNA endoribonuclease (Csy4) and two exchangeable RNA modules.Among the three parts, Csy4, as a member of Cas6 endoribonuclease, cleaves a specific site within its recognition site.This cleavage will result in another cis-repressed RNA module (crRNA) releasing from the masked ribosome binding site (RBS), and the translation of the downstream gene will be activated.Unlike small RNA as translational activator, the endoribonuclease-based activator is capable to efficiently dissociate the perfect RBS-crRNA pairing and activate their downstream translation.The crRNA-RBS duplexes, as one exchangeable module, can be forwardly and reversely engineered to modulate the dynamic range of their translational activity.The Csy4's recognition site, as another changeable module, can be replaced by other three recognition sites of the orthogonal endoribonucleases.Together, the endoribonuclease-based translational activators, with modularized design and predictable functionality, can be integrated in the sophisticated genetic circuits.