The injection branch parameters of the serial resonant injection hybrid active power filter（SRIHAPF） have a great influence on the filtering effect， which few papers focused on. This paper investigates the influences from two aspects: branch harmonic voltage of fundamental resonance circuit and branch harmonic current of injection branch. Considering the harmonic current compensation and the device reliability， a common principle of the parameter designing is proposed. The computation results show that the SRIHAPF designed by the common principle， with a high engineering application value， can meet the requirements of harmonic elimination better than the one designed just by experience.