Abstract: In the new era, General Secretary Xi Jinping has fully and accurately grasped the changes in China's basic national conditions and major social contradictions by further enriching and developing the Party's mass line. His important exposition on the scientific connotation of the mass line in the new era can be summarized as follows: all serve for the masses to solve new contradictions that meet the needs of the people for a better life; all rely on the masses to unite the Chinese forces to realize the great rejuvenation of the Chinese nation. From the masses, thoroughly implement the people-centered development thought; to the masses, firmly seek happiness for the people.