To advance the ability of shipboard X Band TT C System, the scheme is proposed in this paper, which can capture and track the signal of S-band for self-guiding. It can also solve the key technical problems for the narrow beam antenna capture on the X-band signal in ship-sway environment. Dual-band feed is tested,which works in S/X dual frequency band. Based on a detailed analysis of the X Band-downlink requirements, the scheme of the S Band-downlink is givened,which can meet the G/T of shipboard S Band TT C System.It’s function is validated by tracking the FY-3B satellites. The precision analysis indicates that the scheme satisfies requirements.