Abstract: Fungitoxicity is the inherent biological characteristic of fungicide which reflects the activity, safety and effectiveness of the compound. It is a prerequisite for fungicide registration being approved by pesticide registration department and has important value for fungicide creation and rational evaluation. Here, the definition of terms related to fungicide toxicity was clarified and emphasized a series of factors that play important roles in the evaluation of fungicide toxicity, including modes of action of fungicides that have not yet been discovered and the effectiveness of disease epidemic control that which affected by the interaction of pathogen, host and environmental factors. Meanwhile, toxicological mechanisms that interfere with the function of target proteins and structural specificity and precision in the molecular interaction of compound and protein which was important to fungicide toxicological mechanism, were analyzed in depth. The methods of fungitoxicity determination and analysis were also reviewed. The fungitoxicity is an important indicator to measure the quality of fungicide for crop protection. A correct understanding of the concepts of fungitoxicity and its bioassay will be helpful to guide the scientific research of fungicide creation, formulation, application, mode of action and resistance.