Abstract: To scientifically understand the theoretical basis and internal mechanism of the orderly expansion of capital under the conditions of socialism with Chinese characteristics, we must reunderstand the essential characteristics of capital under the different systems of socialism and capitalism. Through rethinking and defining several key issues about socialism and capitalist system from the perspective of capital, this paper focuses on analyzing the internal mechanism of capital disorderly expansion under the conditions of capitalism and socialist system. It is worth paying special attention to that if socialist countries superstitiously believe that the completely laissez faire market economic system advocated by capitalist countries is the best system, give up or weaken the reasonable intervention and supervision function of the government on the economy, split the national economic governance idea that politics and economy are inseparable, and fail to effectively regulate the operation of the market economy and the monopoly behavior of micro enterprises, It will fall into the trap of Neo liberalism carefully designed by Western developed countries against socialist countries, forcing socialism to produce various phenomena of disorderly expansion of capital similar to capitalist countries. On the basis of further defining the two core principles of the orderly expansion of capital under the conditions of socialism with Chinese characteristics and the six important principles derived therefrom, this paper puts forward several key breakthroughs in constructing the theory and policy system of the new mode, new mechanism and new paradigm of the orderly expansion of capital under the conditions of socialism with Chinese characteristics.