We focused on common secondary bonding method that usually applied on manufacturing of FRP yacht, and discussed the secondary bonding strength according to experimental results. The hulls of FRP yacht is made using VARTM, and then the secondary bonding procedures are used to reinforce the hull structures using hand lay-up. The different kinds of resin and different surface treatment methods were considered in this study. Generally, the resin manufacturers always suggested that the secondary bonding procedure can be performed directly after the separation media is released. Therefore, we discussed the bonding strength of different kind of surface treatments, likes grinding, surface sizing, surface-active etc. Finally, the experimental results shown that: 1. The effect of surface sizing is obviously poor than the other surface treatments; 2. The surface-active agent plays a good joint strength on unsaturated polyester resin; 3. Whether the secondary bonding surface is grinded or not, the bonding strengths are not much different.