Abstract: The great founding spirit of the Party is the spiritual source of the Communist Party of China. A deep understanding of the great founding spirit of the Party is of great significance for gathering Chinese forces and realizing great dreams. Analyzing the internal logic of the great founding spirit of the Party is the key to deeply understand the great founding spirit of the Party. The great founding spirit of the Party is the concentrated expression of the CPC's own character. It contains four spiritual characteristics, including "lofty pursuit", "pragmatic style", "practical responsibility" and "political position", of which "lofty pursuit" is the soul, "pragmatic style" is the theme, "practical responsibility" endowment and "political position" are the background. The four spiritual characteristics of the great founding spirit of the Party are interdependent and mutually supportive, forming an organic whole with strict internal logic. "Lofty pursuit" is implemented through "pragmatic style" and "practical responsibility", and is guaranteed by "political position". "Pragmatic style" cannot be separated from the guidance of "lofty pursuit", but also needs to be reflected by "practical responsibility" and "political position". "Practical responsibility" is an important result of adhering to the "lofty pursuit", which is supported by the "pragmatic style" and "political position". "Political position" is the internal requirement of adhering to the "lofty pursuit", which needs to be reflected in reality by "pragmatic style" and "practical responsibility".