Abstract: This paper studies the legal institution of the daily penalty for environmental protection by going through its legislative process and controversy over writing daily penalty into law. After examining Taiwan's related law for this institution,it can be concluded that the daily penalty should not be tagged as administrative penalty and executive penalty in terms of jurisprudence. Clarification of the relationship between the institution of the daily penalty and the principle against double jeopardy leads to a conclusion that the daily penalty is in nature executive penalty in terms of the intention of legislation. In the last session,the paper discusses the ways to expand legal applicability,elaborates the standard of penalty and studies the concept of "being fined","refusing to make correction" and "the duration of punishment" so as to clarify the legal applicability of daily penalty.