The present research investigated homophone density effect in different tasks. Homophone density refers to the number of homophone mates of a Chinese character. In the writing systems such as English, French and German, orthography and phonology have a high degree of overlap. Most of the studies on the neighborhood effects have been conducted with those writing systems. But Chinese has its own characteristics. For Chinese characters, phonology can be isolated from orthography, and one phoneme can have many different graphemes. So there need to be more empirical research done with readers of Chinese. Although there are several experiments to investigate the role of homophone density in the Chinese character identification, few of these studies investigated the effect of the homophone density in normal sentence reading. The current study employed two experiments to investigate the homophone density effect. In experiment 1, homophone density effect was investigated by naming task. It was a one-factor (homophone density: high and low) within-subject design, and in each condition, there were 36 low frequency characters. The structures of the characters under the two conditions were identical. And we matched word frequency, number of radical, number of stokes, power of word-formation and number of meanings for the two conditions. 26 undergraduate students participated in the experiment. The result showed a facilitative effect of homophone density; that is, characters with high homophone density were named faster and with fewer errors. In experiment 2, homophone density effect was investigated in the sentence reading. The design was the same as the experiment 1. We used the 72 characters to form 72 two-character words. All of the 72 characters were in the first place of the words. The words were matched on word property and frequency. And then the 72 words were put into 36 sentences. 31 graduate students participated in the experiment. Their eye movements were recorded with a SR Research Eyelink1000 eye tracker. It seemed that the effect of homophone density is neither facilitative nor inhibitory. The result showed that the context influenced character recognition. In summary, the two experiments indicated that the mechanism of homophone density effects were different in single character naming and in sentence reading task.