Kuramoto-like model is adopted to model a power grid reasonably. And critical synchronization coupling strength and average synchronization error are used to describe synchronization ability and robustness of a power grid, respectively. It is found that power distribution of generators has a great influence on transmission power of lines, and the more high-load lines in power grid, the more difficult the network synchronization. Based on the discovery, we calculate transmission power of each line under uniform power distribution method of generators (EG mode). Then, based on a power flow tracking algorithm, an non-uniform power distribution method (TG mode) of the generators is further proposed. With this method, as the total amount of power generated is given, power of the hub generator node is increased and power of the edge generator node is reduced. It shows that the new power distribution strategy reduces effectively critical synchronization coupling strength and average synchronization error. Thus the method improves synchronization performance and robustness of a power grid.