This research on “Errors in Thai Writing Made by Chinese Students : A Case Study of University of Thai Chamber of Commerce, Academic Year 2008-2009” presents the problems concerning Thai writing errors made by Chinese students. The data for analysis were collected from writing exercises of 57 Chinese students, 399 copies of exercises in academic year 2008-2009.The result are classified into two main types of the Thai-word writing errors: 1) Errors in word level have two points : 1.1 Spelling errors like vowel-form errors, first and final consonant errors and intonation-mark errors or misplacing, and 1.2 Word Usage errors like word-choice errors in terms of meanings, classifications, contexts, conjunctions, auxiliaries and modifiers.The proposed problem solving is concluded in two points; 1) The Thai writing errors caused by mispronunciation can be solved with the accurate-pronunciation practices of those particular words along with the writing practices. 2) The Thai writing errors caused by lack of knowledge of Thai-word characteristics can be solved with the clearer explanation of those particular words based on the Thai norm of language use along with the writing practices in different contexts.