A specific optical system is designed and implemented to study the surface plasmon polaritons waveguides of silver nanowire deposited on the indium tin oxide (ITO) substrate. Fiber optical taper is used to stimulatethe surface plasmon polaritons in the near field. The degree between the fiber optical taper and the silver nanowire is changed by a R axial rotation. The coupling efficiency of the silver nanowire waveguide is researched corresponding to the different intersection degrees. The charge couple device (CCD) digital pictures are caught and the inlet and outlet scattering intensities are calculated by the gray histogram tool in the Adobe Photoshop with a 100 pixel×100 pixel. According to the experimental results, the coupling efficiency is effected by the intersection degree between the fiber optical taper and the silver nanowire, and the value reaches the peak when the angle is 0° and reaches the minimum when the angle is 90°。