Abstract: The truth of Marxism is due to its scientific nature. As a scientific concept, the Marxist historical materialism is the basis of understanding the general rule of human society development. To develop Marxism with innovation in the new era, we must accurately grasp the essence of historical materialism. As a scientific economic concept, Marxist political economy is the key to understanding the special development laws of capitalism. Through the nature of capitalism, we can better understand the concept of "entering the uncertainty and unstable period of the contemporary capitalism". As a scientific socialist concept, the Marxist theory of scientific socialism is the only way to realize the liberation and freedom of human being. Marxism does not end the pursuit of truth, but opens up a way of exploring truth. To promote the innovative development of Xi Jinping's thoughts on socialism with Chinese characteristics for a new era, we must keep practicing, put people the most supreme and keep pace with the times.