In this paper, Co nanorods with extremely high length to diameter and preferred exposed (101) facet were synthesized by carboxyl-assisted over graphite oxide surface. DFT calculation results indicated that (101) facet Co nanorods exhibited higher surface energy of (101) facets (2.61 J/m²) than that of (100) planes nanorods (2.46 J/m²). Such Co nanorods showed very low over-potential for proton reduction, about 0.20 V onset overpotential and 400 and 510 mV at current densities of 2 and 5 mA/cm², and worked as high active co-catalyst for photocatalytic hydrogen evolution. Co (101) nanorods loaded catalyst generated 891.3 μmol H₂ in 2 h, while Co nanoparticles only gave 451.6 μmol of hydrogen during same time. The apparent quantum efficiency (AQE) of Co nanorods catalyst achieved 17.4% at 520 nm. This work opened a news strategy for design of with rodlike structure cocatalyst with preferred exposed high surface energy facet for photocatalytic hydrogen evolution reaction though the carboxylation of GO.