To evaluate the impact of Fuzi on ECG result of mice to explore the relevancy between efficacy and toxicity of Fuzi regarding its effect of restoring yang and saving from collapse.Methods：Different doses of Fuzi were given to mice by gavage, then observed the changes of ECG, measured AST, LDH, cTn-I and the change of heart body ratio.Results：Various Fuzi extract can lengthen interphase of QRS, elevate the segment of S-T, and increase AST, LDH and cTn-I according to the doses. alcohol extracts raised most significantly, and presented side effects at dose of 9 g.Conclusion：Fuzi’ efficacy dose will cause ECG changes and myocardial injury, so monitoring toxicity below the efficacy doses should be paid attention to. To research the relevancy between efficacy and toxicity regarding the “Restoring yang and saving from collapse” effect can minimize toxicity and give full play to efficacy, so that Fuzi has better safety and efficacy.