In this paper, authors show the process of the physical deriving of the Heisenberg Uncertainty Principal under the assumption of the wave function being a displacement function in Schrödinger Equation. This process indicates the Heisenberg Uncertainty Principal is compatible with the assumption of the wave function being a displacement function. It is found that, for a single quantum system, there exists a certainty relationship between the position x and the momentum . If the wave physical characteristics are not considered, then the product of the position and the momentum satisfies the below inequality: ≤ xThat is to say, the Heisenberg Uncertainty Principal is true. ℎ is the reduced Plank constant. If the wave physical characteristics are considered, then the product of the position and the momentum satisfies the below inequality:0 ≤ x < ℎ 2This equation provides theoretical support to Yuji Hasegawa and Masanao Ozawa Experiment. This experiment does not violate the Heisenberg Uncertainty Principal.