It is important to identify the Problem of errors of using Chinese words (in Chinese 'cuobiezi'). Its relevance with students' language competence is clear. In China, researches deal with simplified characters. (in Chinese 'jiantizi') and the contributions aims for “standardisation of words”. This paper deals with errors of using original characters (in Chinese 'fantizi') of junior secondary students. The multiple methods have been employed to investigate the relationship between the frequency of errors and the language competence of students. The results showed that (1) the frequency of errors of using Chinese words reflects the language competence of students; and (2) different reasons attribute to the errors of Chinese words. This paper finally suggests that we should (1) change the 'word count' method in marking Chinese compositions; (2) collect the errors of using Chinese words; (3) encourage students to enlarge their vocabulary and to use more words in their compositions; (4) teach 'ci' instead of 'zi'.