In this study， rose petals were used as the raw material to extract dietary fiber(DF) via the chemical alkali method. The optimal extraction process for DF was determined through a combination of single-factor experiments and the Box-Behnken response surface methodology. A systematic comparison of the structural characteristics， physicochemical properties， and functional activities of soluble dietary fiber both pre-purification (SDF-R) and post-purification (SDF-P) was conducted. The results showed that the extraction yield of 66.42% for SDF was achieved under the optimal conditions of a solid-liquid ratio 1∶39(g/mL)， alkali concentration 6%， extraction time 92 min， and temperature 47 ℃. FT-IR analysis revealed that both SDF-R and SDF-P exhibited characteristic absorption peaks typical of cellulosic polysaccharides， indicating no significant conformational differences in the primary functional groups. Physicochemical property analysis indicated that the water-holding capacity， oil-holding capacity， and swelling capacity of the SDF-P were increased by 2.1%， 11.3%， and 36.7%， respectively. Antioxidant activity assays revealed a decrease in the antioxidant capacity of SDF-P， with reductions of 8.6%， 13.6%， and 32.8% in the DPPH，·OH scavenging rate， and ferric reducing ability， respectively. In contrast， the ABTS+ scavenging rate(99%) showed no significant difference. Similarly， the hypoglycemic function results indicated that the inhibitory effects of purified soluble dietary fiber SDF-P on α-amylase and α-glucosidase were reduced by 4.7% and 8.5%， respectively， compared to the SDF-R， which exhibited stronger inhibitory activity. In summary， the crude SDF from roses possesses superior functionality and antioxidant characteristics， making it an ideal candidate for application as a dietary fiber in the functional food industry.