h-BN samples with different morphology were prepared by microwave reaction with boric acid and melamine as main raw materials. The morphology, structure, purity and adsorption property of the samples were characterized. The results show that:compared with the drying method, the samples obtained by freeze-drying are more slender, and the length-diameter ratio of samples obtained by freeze-drying is 3-6 times higher than that by drying. Compared with the samples without surfactant, the samples with surfactant are more distinct.The addition of salt can not only promote the crystal growth, but also make the morphology of the sample diverse, and produce square and original flake nanocrystals. In addition, the h-BN obtained by the method has more mesoporous and good adsorption capacity for methylene blue, and the adsorption rate of 10 min is as high as 91% or more.