The present invention provides proteins that are suitable to be used as the active ingredient in subunit vaccine against Mocoplasma spp. The present invention also provides a subunit vaccine made therefrom. Said proteins have been experimentally proved to have the capability of inducing sufficient immune response to avoid pigs from Mycoplasma spp. infection. Said vaccine may have one of said proteins as active ingredient; or may have two or more of said proteins and is formulated as a cocktail vaccine. The present vaccine not only is safer than the conventional vaccines but also has equal or even better immune efficiency than the conventional ones. Furthermore, fusion partners suitable for producing said proteins of high solubility are also proved, which can significantly reduce production cost.