Objective To investigate the effect and mechanism of aging on cardiac morphological changes in rats by observing the changes of cardiac fibrosis and activation of inflammatory bodies. Methods A total of 10 SD rats were divided into young group (8 weeks old) and old group (20 months old), with 5 rats in each group. The rats were sacrificed at corresponding time, and the cardiac tissue was harvested respectively. The collagen deposition was detected by Masson staining. The expression of aging markers p16 and p21 was evaluated by immunohistochemical assay. The expression of inflammasome associated proteins Caspase-1 and interleukin-1 (IL-1β) was evaluated by immunohistochemistry and immunofluorescence assays. Image-pro plus 6.0 software was used to analyze the image. SPSS statistics 13.0 was employed to analyze the data, and one-way ANOVA was applied for the comparison between groups. Results Compared with the young group, the collagen deposition was increased [(12.54±2.8)% vs (45.12±7.63)%], the expression of p16 [(21.45±5.21)% vs (38.71±6.89)%] and p21 [(19.23±7.32)% vs (41.01±10.21)%] was enhanced, and the levels of Caspase-1 [(10.23±7.12)% vs (42.01±8.91)%] and IL-1β [(5.27±1.02)% vs (14.62±3.87)%] were elevated in the old group (all P<0.05). Conclusion The occurrence of cardiac fibrosis in aged rats is closely related to the activation of inflammasome signaling pathway.