In this study, protein-conjugated Ag2S nanorods were prepared in aqueous solution, and high-resolution transmission electron microscopy (HRTEM) was used to track the whole process of the nanorod growth. Our results shew that the final products were formed via two-step oriented attachment, that is, particle-particle and rod-rod oriented. More interestingly, before oriented attachment, the nanoparticles or nanorods attached without sharing the same lattice plane; they could then rotate to a perfect array and fuse together by eliminating the two high energy surfaces. On the basis of the calculation of surface energy, two-step attachments and rotations were brought forward, and the role of protein in the forming process of nanorods was discussed.