Pesticides are essential nowadays for agricultural production. For a newly innovated pesticide, three types of assessment are needed before it is authorized, i.e. efficiency assessment, health risk assessment, and ecological risk assessment. The first and primary purpose of utilization of the pesticides was to ensure the high and stable of the yields. After this goal had been achieved, people turn to concern the safety of the yields. Furthermore, they thought that not only the safety of people themselves, but also the safety of environmental organisms and their habitats should be guaranteed. Since it is absolutely impossible to prohibit the use of pesticides in agriculture nowadays, what people can do is to strengthen the management to reduce health and ecological risks caused by them. It is the objective demands of health and ecological risk assessments that push forward generation and development of environmental and ecological toxicology of pesticides.