The factors which cause unreasonable enlargement of income distribution gap in China are various, among which, the imbalance of discourse right between capital and labor, managers and ordinary staff is the very important but neglected one. The imbalance of discourse right makes the ordinary staff at a disadvantage position, and this is the very critical one of the key factors that leads to the increasing gap in income distributions in China. Thus, In order to relieve unreasonable enlargement of income distribution gap, we should push forward the political system reform actively and steadily, promote the trade union reform, and correct the imbalance of discourse right under the leadership of Chinese Communist Party.