In China, the relationship between rural-urban income gap and economic growth rate is nonlinear. When cities’ house price growth rate is larger than critical value, the relationship is negative and income gap will decrease economic growth rate. When cities’ house price growth rate is smaller than critical value, the relationship is positive and income gap will promote economic growth rate. Through experiential analysis, the critical value is estimated, and it is found that China’s present cities’ house price growth rate has surpassed critical value. Therefore, some measures should be taken to lessen rural-urban income gap.