OBJECTIVE The aim of this study was to compare the aneuploidy rates of blastocysts obtained via conventional in vitro fertilization (IVF) using sperm prepared by the swim-up (SU) and density gradient centrifugation (DGC) methods, as detected by non-invasive chromosomal screening (NICS). This comparison would provide more evidence for selecting the appropriate semen processing technique for patients undergoing conventional IVF with NICS. METHODS A retrospective analysis was conducted on patients who underwent conventional IVF and NICS at our hospital from January 2022 to May 2024.Patients were grouped by semen - processing method (SU and DGC groups). Semen parameters before and after processing on oocyte - retrieval day, oocyte numbers (retrieved, MII), and 2PN embryos were compared. Fertilization, cleavage, D3 high - quality embryo, embryo ploidy, and aneuploidy rates between the two groups were analyzed. RESULTS There were no statistically significant differences in multiple indicators such as the number of retrieved oocytes between the two groups (P > 0.05); the rate of high-quality embryos on Day 3 in the DGC group was significantly higher than that in the SU group (53.9 % vs. 48.20 %, P = 0.011).The proportion of embryos with Grade A in the DGC group was 31.8 % (262/824), while that in the SU group was 39.4 % (119/302), showing a statistical difference (P = 0.017). The euploidy rate in the DGC group was 21.7 % (179/824) and the aneuploidy rate was 71.2 % (587/824), while the euploidy rate in the SU group was 25.8 % (78/302) and the aneuploidy rate was 68.9 % (208/302). There was no significant difference between the two groups (P > 0.05). CONCLUSIONS The SU method yielded a higher proportion of Grade A embryos but did not reduce aneuploidy rates, suggesting its potential as a simpler, cost-effective alternative to DGC for NICS in conventional IVF.