Hybrid active power filter (HAPF) has already been an effective and widely-used method for power quality improvement. This paper presents historical review and developing progress of the HAPFs' functionalities as harmonic and reactive power compensation. The structures of HAPFs are discussed in different historical periods, and divided into four developing pattern: parallel active part with parallel element, parallel active part with series element, b-shape, and three-phase four-wire structure. It is aimed at making a comprehensive analysis of HAPFs' historical developing tendency in structure and function design. The future possible developing guidelines are discussed as conclusion in the last.