A method for weaving a three-dimensional preform includes the following steps: decomposing and determining performance requirements of different functional locations of the parts; selecting guide sleeves and fibers of each of the functional locations and designing a parameter; selecting guide sleeves and fibers of a transition area and designing a parameter, thereby implementing smooth transition of the transition area; determining a weaving sequence according to layouts of the guide sleeves and winding manners of the fibers in the functional locations and the transition area to generate a fiber iterative instruction for layer-by-layer weaving; arranging guide sleeves according to design requirements of the functional locations and the transition area to generate a guide sleeve array; and driving a weaving mechanism to select different fibers for subarea weaving layer by layer to obtain the three-dimensional preform having a gradient structure.