Abstract: The concept of“absolute”is one of the core theory of Hegel’s philosophy as well as a complicated one. Hegel didn’t clearly define the concept of“absolute”. But the definition of“absolute”can be clarified by the analysis of internal affinity among Hegel’s concept of“absolute”，Spinoza’s theory of substance，Schelling’s identical ideology of subject and object and Fichte’s self-thought. “Absolute”refers to the organic and all-inclusive whole，being not only an indefinite entity，but also an absolute active subject with internal basis of self-movement. There is an internal paradox in the concept of“absolute”；it overtops itself，transforms to its opposite，synthesizes its opposite to become two necessary parts of new unity with itself and， on that basis，realizes the unity of opposites and the negation of negation. The clarification of the concept of“absolute”can help understand Hegel’s philosophy，and the internal paradox of Hegel’s philosophy can be found in the discrimination of theconnotation of“absolute”.

Key words: the concept of“absolute”, Hegel, Spinoza, Schelling, Fichte, substance, internal affinity