In a blasting demolition project of the bedrock cofferdam of a 300,000-ton dock,it was difficult to excavate shallow points and channels outside the cofferdam due to natural geographical conditions.So,it was necessary to increase the amount of cofferdam blasting to make the front of dock mouth form in one time.This lead to a 68 m long,43 m wide and 14.6~15.6 m deep wide-thick-type blasting demolition of bedrock cofferdam,which width was twice that of similar projects.In order to solve the problems of drilling accuracy,hazardous effects,and control of blasting effects,inclined main blast holes with parallel-fan pattern and vertical pre-split auxiliary holes were used to cover the entire cofferdam to be blasted.In addition,the strategy of dense holes and increased powder factor was adopted to achieve the desired effect of excavation and fragmentation.To control of harmful effects on the protected objects in the dock,high water level blasting supplemented by conventional safety protection was utilized.As for improving the reliability of blasting success and reduce the impact of blasting vibrations,the blast operation team decided to select customized explosive materials,increase the number of in-hole detonators,and connect the initiation network by a V-shape pattern with multiple branches.By summing up past experience,we presented the “super-deep and gently inclined hole drilling method”.Its circulating slag work platform and precise drilling control measures effectively guaranteed the quality,progress and safety of blasting construction.The blasting project was finally successful,and good blasting and excavation results were obtained,which accelerated the overall production schedule by about 2 months,and created nearly tens of millions of economic benefits for the shipyard.