Abstract In the process of coastal bridge construction, cofferdams become necessary facilities to ensure the construction environment dry and safe. However, during the construction period of coastal bridges, extreme surges and waves caused by typhoons can impose huge hydrodynamic loads at the cofferdam and a potential threat to the safety and integrity of cofferdam. Therefore, it becomes valuable to assess the hydrodynamic loads of bridge cofferdam under extreme waves. Meanwhile, in the harsh marine environment, waves tend to propagate in multiple directions. However, previous studies mainly focused on the hydrodynamic characteristics of cofferdam by waves that propagate in one direction. Few studies were carried out on the hydrodynamic characteristics of cofferdam under the action of extreme waves in multiple directions. To fill in the gaps in previous research, this study numerically studied the complex wave hydrodynamics of cofferdam under multidirectional extreme waves. Effects of several major factors, i.e., significant wave height, peak wave period, water depth, spreading angle, incident wave angle and submergence depth were systematically analyzed. It is desired that present research could enhance our understandings on the complex wave hydrodynamics of bridge cofferdam under multidirectional focused waves.