Abstract: It's one of the necessary conditions to apply anti-dumping measures that there is a causal relationship between the dumped imports and the injury to the domestic industry. This paper carefully studies the standard and approaches concerning the determination of the causal relationship, in which there are two kinds of standard,"principal cause" and "one of contributory causes", but the former only accords with WTO's basic spirit. The authenticity of the causal relationship should be base on the examination of all positive and negative evidence.