Chemical vapor deposition (CVD) is widely used for producing high-quality graphene in large area. However, grain boundaries (GBs) are inevitably generated when isolated graphene domains, grown from numerous graphitic nuclei, unify, resulting in severe degradation of intrinsic material properties of graphene. Using mobile hot-wire-assisted CVD (MHW-CVD), here, we successfully demonstrated the progress toward single-crystal graphene; graphene grown from MHW-CVD on pure copper substrate generally has large density of high angle tilt boundary. The main strategy of the improvement is the composition control of catalytic substrate to copper-nickel alloy (4.25 at% of Ni), via both increasing the initial density of graphitic nuclei and facilitating the rotations of isolated graphene domains during the recrystallization process of 2D graphene. Compared to graphene grown from the pure copper substrate, the areal density of the single-crystal graphene from the alloy increases from 22% to 88%. The improvement of electrical property of graphene is also confirmed by the measurement of sheet resistance and mobility whose value is enhanced to 40% and 17%, respectively. Our findings will likely benefit facile CVD synthesis of large-area, high-quality graphene for future thermal, electronic or mechanical devices.