  In this paper, we study a class of Finsler metrics composed by a Riemann
metric $\alpha=\sqrt{a_{ij}(x)y^i y^j}$ and a $1$-form $\beta=b_i(x)y^i$ called
general ($\alpha$, $\beta$)-metrics. We classify those projectively flat when
$\alpha$ is projectively flat. By solving the corresponding nonlinear PDEs, the
metrics in this class are totally determined. Then a new group of projectively
flat Finsler metrics is found.
