Abstract: The socialism with Chinese characteristics in a new era is the scientific socialism based on the "greatest reality" in the primary stage of socialism and adhering to the fundamental principle of a scientific society. It is the socialism with the characteristics of the People's Republic of China on the basis of the historic achievements made in reform, opening up and socialist modernization since the 18th National Congress of the Communist Party of China. According to the basic principle of historical materialism, the new era of socialism with Chinese characteristics is the new era in the primary stage of socialism, and the socialism with Chinese characteristics in the new era is the "basic national conditions" decided in the primary stage of socialism and the realistic socialism with "historic changes". Therefore, the socialism with Chinese characteristics in the new era is still inseparable from the scientific adherence to the theory of the primary stage of socialism. We should embark on a new journey of national construction and complete the historical mission of the Party in the new era by respecting the "basic national conditions" under the existing conditions and the "new orientation" with "historic changes".