Nuclear fission yields a mass of radio-nuclides (half-lives ranging from a fraction of a second to tens of thousands of years or even longer) to follow nuclear fission energy into electric power,and there is a massive release risk to ecological environment. According to sources and the inventory of nuclear chain radioactivity,the paper briefly analyzed the risk characteristics of nuclear chain and the relative comparison. Positive role in Fukushima nuclear disaster "warning" to developing nuclear power lies:as small probability event with high hazard is threatening nuclear safety,nuclear sectors have to abandon the fluke and to persist in "safety first"; To upgrade the nuclear safety standards and design criteria,and win the international consensus ; Alone using PSA results to evaluate nuclear power /reactor safety,especially external events caused,there is a big difference between the uncertainties because of the different database and practice,highlighting the limitations for deterministic adjudgment. therefore,it is not an acceptable and looking forward to nuclear power/reactor safety evaluation of a breakthrough new theoretical method. Based on the present status of China's nuclear power,the problems/puzzles facing the nuclear power development and countermeasures were analyzed from the perspective of sustainable development and ecological civilization construction. <<