Most of the hole accidents in drilling construction are related to the human factors, pure natural accident is relatively rare. The detail analysis was made on the a serious wall collapse accident in ZK3410 hole of Sanshandao offshore gold exploration project, and a series of measures were taken to deal with the accident. The flushing fluid concentration was increased to improve the wall protection effects and hole cleaning was done by dredging the sediment with special drilling tool, until normal drilling operation was returned. The practice proves that the subjective consciousness of the operators is crucial to the hole accidents prevention.