Geographic information system (GIS) is widely used to solve the problems about spatial decision making and strategy planning. However, the potential application in maritime search and rescue (SAR) strategic planning still needs to be opened up. With the theory of accessibility, a new evaluating model of maritime SAR ability was proposed to assess the efficacy of the SAR unit serving a certain sea area by using a key indicator named virtual probability circle (VPC) which stand for the extent of how difficult or how long the SAR vessels reaching the accidental site. In this article, an application to the South China Sea area is shown. Comparing with the SAR abilities before and after new bases settled, the results indicate that the model provides good opportunities for improving maritime management.