The goal of the study is to prove some advantages of graded readers to improve reading skills and read unabridged novels. The two groups are selected receiving 20 lessons in 3 months; one is the experimental group applied to graded readers learning strategy and the other group applied to the grammar-translation learning strategy focusing on grammatical rules and meanings of sentences. Prior to the experiment, a pre-test is conducted to identify the homogeneity of the groups. After the experiment the immediate test in vocabulary and story is conducted and the delayed test in two weeks for the findings of achievement. The control group shows a higher achievement in the immediate test in vocabulary whereas the experimental group does better in story. After two weeks of the delayed test, the experimental group remarkably out performed in vocabulary and story. The experimental group is also proved to have better understanding and less anxiety for reading an unabridged novels. It is strongly suggested that further research enhancing the advantages of graded readers with well developed learning strategies be done benefiting Korean English learners.