  Reliable measurements of the solar magnetic field are still restricted to the
photosphere, and our present knowledge of the three-dimensional coronal
magnetic field is largely based on extrapolation from photospheric magnetogram
using physical models, e.g., the nonlinear force-free field (NLFFF) model as
usually adopted. Most of the currently available NLFFF codes have been
developed with computational volume like Cartesian box or spherical wedge while
a global full-sphere extrapolation is still under developing. A
high-performance global extrapolation code is in particular urgently needed
considering that Solar Dynamics Observatory (SDO) can provide full-disk
magnetogram with resolution up to $4096\times 4096$. In this work, we present a
new parallelized code for global NLFFF extrapolation with the photosphere
magnetogram as input. The method is based on magnetohydrodynamics relaxation
approach, the CESE-MHD numerical scheme and a Yin-Yang spherical grid that is
used to overcome the polar problems of the standard spherical grid. The code is
validated by two full-sphere force-free solutions from Low & Lou's
semi-analytic force-free field model. The code shows high accuracy and fast
convergence, and can be ready for future practical application if combined with
an adaptive mesh refinement technique.
