Abstract: Marx completed the revolution of practical philosophy by criticizing the old materialism and idealism. In his later research， the tension thinking between rational dimension and value dimension in practical philosophy was fully applied in Capital. The rational dimension is mainly embodied in the resource allocation analysis in Capital， and the value dimension in the analysis of the production relationships in Capital. Meanwhile， Capital has an integrative thinking of the two dimensions. The understanding paradigm for Capital， with practical philosophy as its core， has a profound effect on the modern society and provides the theoretical foundation for the mankind to be out of the modern societys dilemma in development.

Key words: Karl Marx, practical philosophy, Capital, rational dimension, value dimension