Abstract: Through the analyses on the distribution of ecosystem, the function of ecosystem, the key ecological problems, the ecological position and the situation of a country in China, the key area on ensuring ecological safety were put forward, the concept and evaluation method were constructed. The ecological position and the situation were the indices which could indicate the importance and the influence on maintaining the safety of ecosystem. The evaluation method on the ecological position and the situation were integrated by the Hanming method and the specialist system. Based on the importance of the ecological position and the situation in country and the principle of constructing ecological barrier structure, the ecological barrier structure was put forward, which was 3 176 076 km2, include four horizontals, two rings and one vertical, relating to 434 reserves,240 state forest parks, 5 international important wetlands and 6 state wetland parks. Moreover, the implementing project and the countermeasure in China were proposed.