We generated a super-resolution optical tube by tightly focusing a binary phase modulated azimuthally polarized laser beam. The binary phase modulation is achieved by a glass substrate with multi-belt concentric ring grooves. We also characterized the 3D beam profile by using a crossshaped knife-edge fabricated on a silicon photo-detector. The size of the super-resolution dark spot in the tube is 0.32λ, which remains unchanged for ~ 4λ within the tube. This optical tube may find applications in super-resolution microscopy, optical trapping and particle acceleration.