The rapidly growing international trade constantly causes the concerning of the environmental protection, and thus forces EU to take the TREMS to tackle the trade-environmental tensions. After the spotlight on the legal competence of EU on these TREMS, six main aspects and three noticeable areas (the wildlife, waste and the eco-labeling scheme) of the contents of the TREMS are scrutinized. The trade influence from that is very conspicuous. Deliberating on the essence of these TREMS, there are two relevant issues: PPMs and the Precautionary Principle. The use of PPMs is a core issue in the several TREMS of EU. The status of PPMs in the international trade rules is unclear according to recent cases. The precautionary principle is seen as fundamental principle of EU in the environmental field. EU regards it as a general customary rule of international law or at least a general principle of law. This is not accepted or objected by the Appellate Body in the Hormones case. The legal status of the precautionary principle under the WTO rules is not clear until now. The TREMS of EU could be regarded as trade barriers in the ordinary meaning in which tariff is a kind of trade barrier. Because the legal statuses of PPMs and precautionary principle are not clear, the legal status of the TREMS of EU is unclear until now. Therefore, it is not suitable to say that the TREMS of EU constitutes a new kind of trade barriers which violate the WTO rules. Key Words: TERMS, environmental protection, PPMs, environmental standards, precautionary principles, trade barriers, eco-label, WEEE, international trade rules,