As the only source of value creation, labor embodies the essential characteristics of human beings. It is not only an objective act of the human in transforming nature, but also a subjective goal of human beings. From the perspective of epistemology, the labor value can be understood from the two aspects of to-be and ought-to-be. The value of to-be embodies its value of material wealth, and the value of ought-to-be reflects its humanistic and spiritual value. As Marx pointed out that the labor is the only source of commodity value. Under the historical background of the new era, the real value of the labor is the logical starting point for people to have more senses of acquisition. As happiness is the subjective feeling that people can realize their own value through the labor, real labor happiness is shown in the free and all-round developments of human beings. Sublating the alienated labor, attaching importance to happiness, and realizing the unity of to-be and ought-to-be in the labor value are the time elaboration of the new era of labor values.