Abstract: The discipline of pesticide ecotoxicology stretches across toxicology, pesticide science, and ecology. The pesticide ecotoxicology and the pesticide environmental toxicology were compared from four aspects, i.e. ‘organisms in concern’,‘levels in concern’,‘discipline affiliation’ and ‘practical employments’. Methodology of the discipline was outlined from a few aspects, such as ‘test spans’,‘dosages selected’,‘controllability’,‘exposure estimations’,‘research phases’, etc. The outstanding feature of the discipline is that it pays more attention to non-target organisms apart from the human being and favors to study them from ecological point of view. The hazard estimation experiments can be classified as‘acute’, ‘subchronic’ and ‘chronic’, based on the test spans, and they can be divided into ‘indoor’, ‘semi-field’ and ‘field’, according to the controllability of the experiments. From economical and temporal point of view, the experiments should start from acute and/or indoor, and followed, if necessary, by chronic and/or field. To avoid ‘false negative’ results, one must ensure that the organisms be exposed in severe stress in indoor experiments compared with those being exposed in field experiments. Considering the diversity and complexity of agricultural ecosystems, ecotoxicologists should consciously accord the items and the methodologies of their researches to the requirements of risk assessment. Only then the ecological senses of them could be properly revealed. Along with deepen in understanding of the interaction between pesticides and ecosystems, the discipline of pesticide ecotoxicology would progress in both theory and practice and this would in turn promote ecological risk assessment of pesticides.