Indium Phosphide (InP)-based hybrid plasmonic waveguide for nanoscale optical confinement and long-range propagation at wavelength 1.55 µm has been proposed in this paper. In this structure, the InGaAsP layer is designed as a ridge with a gold cap by intervening a ridge of the InP layer between them. InGaAsP lattices are suitable for that of an InP substrate. In1 − xGaxAsyP1−y was graded in refractive index by changing the mole-fraction. Using a graded index, the confinement and the propagation length can be improved compared with the conventional one. Propagation length of 40 µm is achieved with better confinement as compared with the traditional hybrid ones. Changing only the y parameter with constant x, we get a propagation length greater than the inverse case, that is, changing only the parameter x, as well as better than the base case when the scaling is not included in the design. This is in parallel with good results in the mode effective area( Aeff) and Figure-of-merit (FoM) for the same condition of changing y which expresses a good confinement condition. The pioneering program COMSOL Multiphysics was used to simulate the designs proposed in this paper.