The invention provides a method for performing surface modification on the inner wall and the outer wall of a tube by adopting atmospheric-pressure plasma and belongs to the technical field of surface treatment of plasma materials. The method comprises the steps that produced plasma jet is applied to the surface of a to-be-processed tubular material, working gas is introduced into the to-be-processed tubular material, and plasma is formed in the to-be-processed tubular material; the plasma jet performs surface modification on the outer wall of the to-be-processed tubular material; meanwhile, an electric field for ionizing the working gas in the to-be-processed tubular material is provided, so that the plasma is generated in the tube and realizes surface modification on the inner wall of the to-be-processed tubular material; when the to-be-processed tubular material performs rotating and feeding motion in the axial direction, surface modification on the inner wall and the outer wall of the tubular material with any length can be realized. According to the method, complicated vacuum equipment is not needed, simultaneous modification of the inner wall and the outer wall of the tube with any length is realized by controlling motion of the processed tube, the cost is low, the operation is simple and flexible, environmental pollution is avoided, and the method for surface modification is environment-friendly.