To obtain high-purity cylindrical vector beam pulses， a wavelength-switchable passive mode-locked cylindrical vector beams all-fiber laser is proposed and constructed based on a symmetrical two-mode coupler. First， the refractive index matching diameter for the conversion from the fundamental mode to the higher-order mode was obtained based on the principles of fiber optic transmission. The influence exerted by the structural parameters of the symmetrical two-mode coupler on mode selection and coupling characteristics was analyzed， employing simulations of mode coupling theory and the beam propagation method. The symmetrical double-mode coupler was fabricated utilizing the fusion tapering method. This method eliminates the complicated pre-taper process commonly employed in traditional mode selection coupler production. Finally， a passive mode-locked all-fiber laser， based on the symmetrical two-mode coupler， was constructed. This laser showcases a switchable central wavelength of 1 039 nm and 1 068 nm， pulse repetition interval of 113.8 ns， repetition rate of 8.78 MHz， pulse durations of 660 ps/656 ps， and maximum output average power of 5.25 mW/5.2 mW. In addition， it achieves a mode purity of over 97% for the vector beam output. The conducted experiments validate the feasibility of the symmetrical two-mode coupler and present a viable solution for obtaining high-purity cylindrical vector beams in future applications.