Objective To analyse the efficiency of causality judgement indicators of adverse drug reactions (ADR). Methods Causality judgement indicators of ADR were collected by literature review, 14 indicators (reaction time, withdrawl symptom, a second drug application, similar report, another evidence, similar response, dose change, plasma drug concentration, placebo, combined medication, family history, past history, baseline disease and non-drug factor) were determined as key indicators for efficiency of causality judgement of ADR by expert interview, and questionnaires were designed. Sixty-five staff from Shanghai Food and Drug Administration and medical units were surveyed, and 61 (94%) effective questionnaires were recovered. Factor analysis was conducted on the basis survey findings, and the role of each indicator in causality judgement was obtained by variance calculation.The minimum number of causality judgement indicators of ADR was determined by dimension reduction method. Results Kaiser-Meyer-Olkin and Bartlett tests revealed that there existed relevance among various indicators. When the number of indicators reduced to 7, the efficiency was ≥85%. The relationship among 7 indicators (past related indicator, information evidence indicator, withdrawl reaction indicator, plasma drug concentration indicator, time indicator, control indicator and similar case indicator) were illustrated by score function. Judged by 7 indicators, nearly 15% information was not included, and might lead to false judgement. Conclusion More factors should be included in the causality judgement of ADR in the establishment of compensation system for ADR to ensure social justice.