The major purpose of this article is to research writer`s informational- transforming mode in writing informational text. This paper investigates how a writer expresses the information that he gets in reading resources and analyze the correlation between writing quality and informational-transforming mode. The aspects of writer`s informational-transforming mode are categorized in three criteria; content, organization or order, and expression type(lexico-grammar). The four categories of informational- transforming mode are ``plagiarize``, ``quote``, ``paraphrase``, and ``innovate``. The most observed value is the ``plagiarize`` in 6th grade and ``paraphrase`` in 4th grade. The correlation analysis between writing quality and informational- transforming mode accounts for the result; the more writing quality is high the less likely the sentences plagiarized the resource information, and the more writing quality is high the more likely the sentences that paraphrase in his own words and innovate new information. This research emphasizes the importance of paraphrasing the resource information in his own words in writing informational text. Students can construct new knowledge by synthesis of information that he has already known and new information through information-transforming process. Information-transforming process will be the process of knowledge construction.