In this paper, an improved dead-beat controller (DBC) for a single-phase LC-coupling hybrid active power filter (LC-HAPF) is proposed to achieve both low steady-state error and fast transient response. The conventional DBC has an inherent discretized and predictive error, which can increase the steady-state error. Thus, a signal correction technique is used to reduce the steady-state error. Moreover, the improved DBC is implemented with a coupling capacitor voltage observer to replace the voltage sensor, thus reducing the system cost. After that, the stability analysis and parameter design of the proposed improved DBC for the LC-HAPF are given in detail. Subsequently, to verify the effectiveness of the improved DBC, the simulation results are provided in comparison to the conventional DBC.