Since 1960, the world’s income gap has been inverted U-shaped with 2000 as its inflection point. But the differentiation of income gap between countries in different income levels and between countries in different regions has been obvious.The research in this paper is based on three economic growth facts that have emerged in recent decades: the continuous increase in the share of capital income in various countries, the unconditional convergence of manufacturing, and the success of catching up with countries showing increasingly higher capital accumulation trends.