Abstract: In order to acquire the characteristics of long-range surface plasma wave, such as the resonance angle, full width at half maximum of resonance peak and depth of attenuation peak, a prism coupling method was used to excite the long-range plasma surface wave of media-metal film-media symmetrical structure. The influences of the changes of material film material, metal film thickness, medium refractive index, medium thickness and other parameters on the characteristics of long-range surface plasma wave were studied. The results show that, the full width at half maximum of the attenuation peak of long-range surface plasma wave is narrower about 1 or 2 orders of magnitude than that of traditional surface plasma wave. When the dielectric film thickness is 500nm and 1300nm, the attenuation depth of plasma surface wave is only about 1/2 of those of dielectric film thickness 700nm and 1000nm. The full width at half maximum decreases with the increasing of dielectric film thickness. The thinner metal film is, the deeper attenuation depth is, the smaller full width at half maximum of attenuation peak is. The changes of medium refractive index has no obvious influence on full width at half maximum. The various metal film parameters will change the position of resonance peak. The study provides the effective basis for the application of long-range surface plasma wave in sensing, waveguide, and biosensors field.