Abstract: The truth has its own self. We can conduct research into the self theory; the truth does not own the self theory meaning at all. So if it is endowed with self theory meaning, the unexpected problem will appear. Only if the cognition definition is involved, can the truth concept be reasonably solved. It is inpossible that the truth is the union of objective truth and specific truth. In contrast the truth only can be defined as on the basis of practice the cognition main body is the right reflection of the nature and law of cognition object.