The invention discloses a Kirchhoff beam migration method under complex topography. The Kirchhoff beam migration method comprises the following steps: inputting relevant parameter files, migration velocity model files and seismic records; dividing the seismic records of each shot into a plurality of different time domain data volumes with a window center as a core, and then decomposing the data into plane waves; tracing rays from shot points along different directions, and calculating the corresponding information of the grid nodes within the scope of a sectional radial beam for storing each ray; tracing the rays from the window center along different directions, and calculating the corresponding information of grid nodes within the scope of the sectional radial beam for storing each ray; selecting the beam from the shot points and the window center for imaging calculation; and accumulating the imaging results of all of the pairs of the beams so as to obtain the migration imaging results. According to the Kirchhoff beam migration method, the coverage of beams in shallow model is increased, and the imaging quality of the Kirchhoff beam migration method in a shallow structure of complex topography model.