Owing to the crucial role of the CO reduction in the sustainable development and carbon neutrality, designing tunable electrocatalyst with high efficiency is the top priority for the controllable CO reduction reaction (CORR). Inspired by the interlayer van der Waals coupling modification, we have theoretically explored the tunable catalyst for the CO electrochemical reduction based on the bilayer C3N (b-C3N) via the rotation, translation and transition metal intercalation. Through careful computational screening, we found that rotational and/or translational intermodulation to the transitional metal intercalated b-C3N (TM/b-C3N) can tune its catalytic activity and selectivity efficiently and therefore control the reaction rates and final product distribution. The electronic analysis revealed the half-metallic characteristic of the TM intercalated b-C3N and found that the electrons transferring from the intercalated metal to the adsorbed molecules with the rotated (or translated) b-C3N acting as transferring bridge can further activate the catalyst surface. This study provides a new strategy to design novel CORR catalyst with tunable catalytic activities by mechanical operations, such as rotation, translation and intercalation, and will open a new door for the application of controllable COx reduction.