By comprehensive analysis and design optimization of barrier structure parameters, a new type of beam-and-post steel barrier was invented according to impact test condition and acceptance criteria of cross-sea bridge barrier. Full-scale impact tests and finite elements analysis were conducted to do safty evalution of the barrier. The results show that, ASI value is 1.62 for test and that is 1.67 for FEA, THIV is 30.7km/h for test and that is 31.2km/h for FEA. Working width is 0.88m for test and that is 0.62m for FEA. Occupant risk evaluation index can meet the requirements of level B and the working width can meet the requirements of level W3. Both of tracking and posture of vehicles are well. The study results above show that safety performance of cross-sea bridge barrier can meet or exceed the acceptance criteria. FEA results are consistent with Full-scale impact test, which validate the reliability of FEA. cross-sea bridge barrier can meet the highest test level for beam-and-post steel barrier, which can defend the out-of-control vehicles effectively and help to ensure the bridge safety.