Plasma source ion implantation is a non-line-of-sight ion implantation technique for surface modification of materials, but that technique is only suitable for outer surface modification of hollow targets, not for inner surface modification. In this article we present a new method that applies to inner surface implantation. Preliminary experimental results show that this new method increases plasma density and uniformity inside the tubular tar-get with the inner surface, generates a plasma sheath between the inner surface of the target and the plasma to implant the inner surface of the target effectively, and achieves a dose uniformity that is acceptable for industrial applications.