The present study was designed to investigate the relation of decoding ability with character complexity effect and word length effect when reading Chinese script. Character complexity was defined in two ways: (1) the number of constituent strokes for characters (Experiment 1), and (2) the number of constituent radicals for characters (Experiment 2). Length was defined as the number of constituent characters for words (Experiment 3). A lexical recognition task was used in three experiments. The participants consisted of 45 third graders with low decoding abilities, 42 third graders with average decoding abilities, and 37 third graders with high decoding abilities. The findings are as follows. First, when high frequency characters were selected as stimuli and character complexity was defined as the number of constituent strokes of characters, third graders with different decoding abilities showed character complexity effects; however, the slop of low decoding ability group was steeper than those of average and high decoding ability group. Secondly, when character complexity was defined as the number of constituent radicals of characters, third graders with different decoding abilities did not show character complexity effects. Thirdly, when the length was defined as the number of constituent characters of words, third graders with different decoding abilities showed word length effects.