In this study, Polypropylene (PP) reinforced by nanocellulose/attapulgite composites (NCC/AT) was prepared. The mechanical properties and aging resistance of modified PP were studied. The morphology of modified PP was characterized by Scanning electron microscopy (SEM). The structure between NCC and AT was detected by Fourier transform infrared spectroscopy (FTIR). The proportion of NCC and AT on the mechanical properties of modified PP was investigated. The effect of the content of NCC/AT composites on the mechanical properties and aging resistance of modified PP were investigated. The results revealed that NCC/AT composite materials were prepared, and uniformly dispersed in the PP matrix. When the ratio of NCC and AT was 100:3 (m1/m2), the tensile strength and impact strength of modified PP were 32.85 MPa and 21.61 J/m, respectively. In addition, the tensile strength of modified PP with 3 wt% NCC/AT composites increased by 14.7% compared with pure PP. After 15 days of thermal aging, the retention rate of the tensile strength of modified PP was 98.81%, which was 5.16% higher than that of pure PP. The retention rate of impact strength of modified PP was 95.05%, which was 56.59% greater than that of pure PP.