The invention, belonging to the field of 
surface modification on materials, relates to a 
magnetic field for plating on inner wall of long 
pipe and a field-enhanced arc 
ion plating device, characterized in that: the 
magnetic field is used to restrain and control the 
plasma beam motion trail in the arc 
ion plating process, two sets of 
magnetic field generators are arranged in an arc 
ion plating deposition device, one set is arranged on the 
plasma transmission channel outside a 
vacuum chamber for using the magnetic field to focus the 
plasma beam and restrain the 
diameter of cross section and transmission efficiency when transmitting the 
plasma beam, and the other set is arranged on the outside of a tubular workpiece in the 
vacuum chamber for guiding the 
plasma beam to diffuse along with the central axial direction of the tubular workpiece; field enhancement is used in arc 
ion plating for using the magnetic field to realize accelerated directional flow of plasma, a pulsed 
electric field is arranged in the workpiece; the magnetic field and 
electric field are used to restrain and control the 
plasma beam, so as to realize the 
coating deposition of the plasma on the inner wall of the tube. The invention is suitable for depositing coatings on the inner wall of tubular workpiece which is used as the service surface.