This paper investigates the linear stability of a liquid jet exposed to the subsonic crossflow with aluminum particles and surfactant. A dispersion relation for the disturbances at the interface is obtained. The characteristics of metal particle are shown in the expressions of liquid density, viscosity, and surface tension. The results reveal that the non-dimensional surface tension gradient and surfactant diffusivity show their strong coupling effects on the instability features. The maximum growth rate and cutoff wavenumber reduce with the increase of surface tension gradient when the surfactant diffusivity approaches zero. The maximum growth rate increases while the cutoff wavenumber rarely changes with the enhancement of surfactant diffusivity when the effect of surface tension gradient is ignored. The effect of surface tension gradient or surfactant diffusivity on the instability characteristics also relates to the Laplace numbers when the effect of the other one parameter cannot be neglected. In addition, the effects of other non-dimensional physical parameters such as the liquid Reynolds number on the instability features at the interface are discussed as well.