A T-shaped splitter of the surface plasmon waveguide with a stub based on metal-insulator-metal structure was proposed. The relationship between transmission and structure parameters was investigated by Finite-difference time-domain method. The simulation results show that the periodical changes of surface plasmons power can be achieved by changing the width and length of stub structure in T-shaped waveguide. Also, the periodical changes of splitting ratio for changes of surface plasmons can be obtained by changing the stub structure position of the output port in the metal-insulator-me waveguide structure. When the splitting ratio get maximum(or minimum), T-shaped splitter can achieve the unidirectional propagation of changes of surface plasmons. Besides, the periodical changes of splitting ratio was explained based on the changes of surface plasmons interference theory.