Kant's conception of 'culture' is largely confined to his later works in the field of history, anthropology, and teleology. But no research has so far exclusively analysis the meaning of culture in Kant's Critical Philosophy, and also the metaphysical and philosophical foundations of this concept. Also, due to the vague and irregular use of the terms Kultur and Bildung (and combining them with concepts such as Zivilisation and Erziehung) in the second half of the eighteenth century, in the intellectual space of Germany, the understanding of the meaning of culture is largely obscure and controversial. Therefore, the present paper not only limits the scope of its discussion to Kant's critical philosophy and its three major books (Critique of Pure Reason, Critique of Practical Reason, and Critique of Judgment, with the consideration of Groundwork of the Metaphysics of Morals), and not only has shown the usage of the Kultur and Bildung in these works, but also has always focused on the theoretical and metaphysical foundations of these applications. In a word, the present paper tries to clarify the meaning and implications of these terms by categorizing the subject matter and the analysis of different practices of Culture (whether in the Bildung or Kultur form) in three of Kant's main books, and ultimately answering this main question that 'What does the term "culture" mean in Kant's critical philosophy'?