Abstract: In the recent years, the application of Ba isotope researches in the ecological and environmental fields on earth surface has become more and more extensive. However, a large amount of fission materials, which include fissiogenic Ba decayed from radioactive fission products, have been released to the environment through nuclear weapons testing in the last century, nuclear accidents, nuclear power plant operations as well as discharge from the reprocessing plants of spent nuclear fuel. These fissiogenic Ba could contaminate the natural samples on the surface and modify their Ba isotope characteristics, which is not conductive to development and application of Ba isotope research in this field. However, few studies have been focused on the influence of fissiogenic Ba to the environment. According to the previous and new data available, the Ba isotope distribution in different earth surface reservoirs was reviewed in this paper. Meanwhile, on the basis of nuclear fission theory, Ba isotope compositions of the fission products and their effect on the natural Ba compositions were calculated. The result shows that the natural Ba compositions can be obviously modified by fissiogenic Ba contamination, thus need to be payed attention. In addition, based on the calculation results, it was found that the simultaneous measurement of δ^137/134Ba and δ^138/134Ba values could effectively exclude the contaminated samples, according to their abnormal characteristics.