The aim of this study was to develop an effective method for decreasing the content of histamine and the immunoreactivity of parvalbumin in Decapterus maruadsi. As demonstrated by reverse phase high performance liquid chromatography, no effect on histamine content was found when fish were treated by boiling (100 °C), ultrasonication, ultraviolet irradiation, pressure treatment (121 °C, 0.12 MPa). However, the histamine content was reduced by 73.55% when the Maillard reaction was combined with pressure treatment (MPT). Further, the allergenicity of parvalbumin was retained after boiling, ultrasonication and ultraviolet irradiation, but was effectively decreased when fish were treated by MPT. Animal experimental results showed lower levels of IgE, IgG1 and IgG2a and contents of serum histamine when measured in a group of MPT sensitized mice. These results showed that the MPT is an effective method for simultaneously reducing the histamine content and the immunoreactivity of parvalbumin from Decapterus maruadsi.