Deadbeat control algorithm has good real-time performance and high precision, but it depends heavily on exact circuit system model. This chapter systematically studies the grid-connected current controlled by deadbeat algorithm in single-phase grid-connected inverter in different filter modes such as the single inductance L filter, the second-order LC (inductance and capacitance) filter and the third-order LCL filter. Based on the classical control theory, mathematical models of the inverter system were deduced in deadbeat control under the different filter conditions. And the design idea was described in the chapter. For the problem that resonance easily occurred in LCL filter, which brought difficulty in system design, two resonant rings in the circuit topology were inhibited by improving the structure of capacitance C. The computer simulation results showed that the waveform smoothness of grid current gradually improved with the increase in the number of filter order. At last, in a 3 kw prototype, the related hardware and software design were carried out, and the effectiveness and feasibility of high-order deadbeat control algorithm were verified.