It is vital to improve the deadbeat control algorithm. There are disadvantages of the traditional algorithm, such as the pulse width limit and phase delaying. The improved algorithm, which combines the prediction algorithm and the deadbeat control, can calculate the switching duty cycle of photovoltaic grid-connected inverter in advance and output timely. In this paper, this new method is introduced in detail, and the advantages compared to the traditional algorithm are presented. Simulation experiments are done based on both algorithms. The results verify that the phase of output current tracks the grid voltage better. The power factor is so closed to 1 and the current quality is largely improved.