In this study, polyurethane (PU) was synthesized using 4,4,-diphenylmethane diisocyanate as a hard segment, polytetramethylene glycol and polycaprolactone diol as soft segments, and 1,4-butanediol (1,4-BD) as a chain extender. Thermally treated attapulgite (TAT) was added to the PU matrix to prepare TAT/PU nanocomposites. The TEM, FT-IR, XRD and EDS were used to characterize the structure and morphology of the TAT/PU nanocomposites. The TEM results show that TAT maintains its rod-like structure in the PU matrix. The results showed that the addition of a small content of TAT resulted in no obvious changes in the Fourier transform infrared (FT-IR) spectra. XRD results showed that the main crystalline peak of TAT became more pronounced with increasing content of TAT, and EDS showed that the content of Si increased with increasing content of TAT in the TAT/PU nanocomposites. The thermal and mechanical properties were optimal at 2 wt% TAT. When TAT was added at 5 wt%, agglomeration occurred, resulting in a decrease in the thermal and mechanical properties of the TAT/PU nanocomposites. Contact angle and AFM results showed that the hydrophobicity and surface roughness increased with increasing content of TAT. SEM showed that the hydrolytic degradation was affected by the test temperature, test time, and the content of TAT. Moisture absorption tests showed that the moisture absorption of TAT/PU nanocomposites increased with increasing content of TAT and higher environmental humidity.