By exploiting the concept of row partitioning, we propose an efficient variant of the greedy block Kaczmarz algorithm for solving consistent large linear systems. The number of blocks is determined a priori through numerical experiments. The new algorithm works with a reduced linear system, which dramatically diminishes the computational overhead per iteration. The theoretical result validates that this method converges to the unique least-norm solution of the linear system. The effectiveness of the proposed algorithm is also justified by comparing it with some block Kaczmarz algorithms in extensive numerical experiments.