In this paper, a new type of surface plasmon waveguide system was proposed and its mode characteristics and the optical force exerted on the nano particles were studied. By the calculation of numerical simulation and theoretical analysis of the system through the finite element software (COMSOL), it is found that a deep sub wavelength energy bound can be formed in the gaps of the nanoscale structure. Due to the strong coupling effect between the two waveguide structures, the optical force increases at least one order of magnitude compared with some existing surface plasmon waveguides and reaches over 4200fN/W. The local scope of the captured particles is only a few dozens of nanometers. The waveguide system proposed in this paper can be used for the design and research of powerful and high-precision nanoscale optical tweezers.