Using the in-line (IL) forced oscillation test data of rigid cylinder, an IL vortex induced vibration (VIV) prediction program for deepwater riser is constructed. The program takes into account the effect of cross-flow (CF) vibration on the IL vibration by introducing IL excitation amplification factor. Generally, there may be some overlap regions in the power-in zone associated with different modes. Under the assumption that the shedding vortex modes associated with different instability region are mutually independent, a method is applied to handle with the overlap regions. The HanØtangen test riser is predicted using the present model, the obtained displacement RMS and the main induced modes matching well with the test data. In order to broad understanding for the IL induced fatigue, fatigue damage analyses are carried out for a deepwater riser by use of S-N approach. Based on these, the effect of power ratio cut-off value, top tension and current profile on the fatigue damage are discussed, and some useful conclusions are obtained.