A novel optical element, step refractive index triangular prism, for generating non-diffracting linear structural beam which has higher intensity in the central spot is proposed. The problem that the energy of non-diffracting linear structural beam generated by uniform refractive index triangular prism is evenly distributed and the energy efficiency of central spot is low is solved. The formation mechanism of the non-diffracting linear structural beam which has higher intensity in the central spot is analyzed by geometric optics, and the relevant parameters are also calculated. The intensity distribution is simulated by diffraction integral theory. The results show that when a plane wave illuminates the novel optical element, a non-diffracting linear structural beam which has higher intensity in the central spot is formed.