Hydrodynamic analysis of a seventh generation ultra-deep water drillship is carried out to solve added mass and response amplitude operator. Short term response prediction is made for the South China Sea, west Africa and Brazil offshore oilfield environment conditions. The operation capabilities of drilling, well testing, running BOP and riser disconnect operations in different wave direcions are studied and weighted operation capabilities in different areas are presented. Besides, the available period/wave height combinations are analyzed. The results can provide reference to the design and operation of drillship.