Inspired by the functional microstructure of the ant nest, a humidity control material was prepared by the sintering of modified low-grade sepiolite. A hierarchical porous structure accelerates the diffusion of water vapor. Meanwhile, CaCl2 was applied subtly to enhance absorption/desorption of water vapor in response to the change of air relative humidity. The water vapor adsorption desorption content reaches 550 g.m(-2) with a steady performance after 10 cycles. The flexural strength of the specimen is excessive, 10 MPa. Furthermore, two model houses were used to evaluate the performance of the material in a real environment. The result indicated that it could narrow indoor humidity fluctuation by more than 10% RH spontaneously and mainly maintained the humidity within a healthy range (RH 40-70%) without energy consumption. This invention makes it possible for large-scale fabrication of this material in terms of wall bricks for smart indoor humidity control.