The embodiments of the invention provide a method and apparatus for constructing an interference matrix. The method comprises the following steps: obtaining a to-be-detected cell service amount and frequency application information of each cell to be detected in a communication area; according to the to-be-detected cell service amount and the frequency application information, calculating a user number of each carrier frequency; and according to the user number of each carrier frequency, the to-be-detected cell service amount, the frequency application information and information of other cells corresponding to each cell to be detected, calculating the interference matrix of the communication area, wherein the interference matrix is used for calculating the total probability that each cell to be detected is interfered by N other cells. According to the invention, the interference matrix is established based on the service amount of each cell to be detected, the constructed interference matrix can reflect the interference influences exerted by other cells of each cell to be detected in the communication area, the interference matrix establishing process does not require numerous tests any more, and the interference exerted by all other cells on each cell to be detected can be calculated in real time.