The invention relates to a method and device for determining a decision threshold of DTX detection, and a DTX detection method and device. The method for determining the decision threshold comprises the following steps: determining a target terminal number range where a current terminal number is located according to the current terminal number on a target physical resource and multiple pre-divided terminal number ranges; determining a target signal to noise threshold and a target relative power threshold corresponding to the target terminal number range according to a pre-established corresponding relation among the terminal number range, the signal to noise threshold and the relative power threshold; dynamically adjusting the target signal to noise threshold and the target relative power threshold according to a physical measurement value, and determining the adjusted target signal to noise threshold and the adjusted target relative power threshold as the decision threshold of DTX detection. According to the DTX detection method, the decision threshold determined by the method for determining the decision threshold of the DTX detection is used for performing the DTX detection of each terminal on the target physical resource. By adoption of the technical scheme, the DTX detection performance can be improved.