There are two backgrounds when the concept of "aesthetic non-differentiation" is put forward. The background of thought is critique of Kant's subjective aesthetics and its successors, such as genius aesthetics and experience aesthetics. The real background of art practice is the critique of the so-called "museum-style art". The theoretical essence of "aesthetic non-differentiation" is the emphasis on the unity and non-differentiation of the whole life world and ontological truth as a representation of the life world. The directly and mainly theoretical source of "aesthetic non-differentiation" is Heidegger's ontological thought. The misreading of Heidegger's ontological aesthetics causes some theoretical defects in "aesthetic non-differentiation" itself, such as the superficially aesthetic thought, the statically aesthetic understanding. "Aesthetic non-differentiation" is a key concept in the early Gadamer's aesthetics. The reflection and critique of the concept is a reflection and critique of the early Gadamer's aesthetics in fact. The reflection and critique of "aesthetic non-differentiation" offer us the enlightenment that keeping an identical as well as differential tension is necessary between art and historical reality, and also between the aesthetic and the non-aesthetic.