An air channel inside a silver metal film is usually used as a typical Channel Plasmon Polariton(CPP) waveguide.This paper presents research on the basic properties of this waveguide using the Finite Difference Time Domain(FDTD) method.The relationship between transmission power and structure of the waveguide is investigated.The simulation results show that the subwavelength trapezoidal CPP waveguide is superior to the rectangle CPP waveguide for controlling SPP radiation loss and enhancing the transmitted power.As a result,if the rectangle CPP waveguide is replaced by a trapezoidal CPP waveguide in certain integrated optical devices,their performance may be improved.