Anchoring radius is vital to anchoring safety in that it is not only an important datum for judging whether the vessel is dragging or not，but also an important basis for setting reasonable GPS receiver ANC alarm.Previous work on anchor radius calculation formula is summarized according to related specification of anchor radius.The regression analysis of measured data is analyzed by software SPSS，and the relationship between regression curves of measured data and the values derived from previous formula is analyzed.The application circumstances are discussed and new formula for anchor radius calculation is drawn.The work provides a theoretical basis for navigation practice and ensure the safety of anchoring.