The purpose of this paper is to conduct quantitative and qualitative analysis concerning the advent of interlanguage during the usage of affix among Chinese Korean language learners, as well as to analyze errors and inter the reason behind those errors from language learners. The ratio of affix used increased from learners in level 4 and similar levels were observed from level 4 or above. The ratio of affix used by learners were less than that of the textbook. The variability of affixation use was significantly changed between the 5th and 6th grade, The regression rate of suffixes was higher than that of prefixes. Also, when suffixes were classified based on the degree of significance which contribute to roots, the proportion of affixes with 'strong vocabulary meaning' from level 1 to level 4 decreased steadily according to the degree of proficiency. The ratio of affix errors did not change significantly from beginner to advanced level, but only slightly higher in learners in level 6. Of the 26 prefixes and 112 suffixes, 5 prefixes and 43 suffixes occurred with errors. ‘-toyta’, ‘-hata’, ‘-i32’, and ‘-hi7' appeared with error in all proficiency levels. Finally, concrete examples of errors were presented according to their aspects of errors and the part of speech of compound words where errors occurred. This study is meaningful in that it analyzed the use of affix based on the large scale learner corpus with pseudo-longitudinal materials from Chinese Korean language learners. (Yonsei University)