Objective To investigate the dynamic changes and correlation between splanchnic tissue oxygen saturation (SrSO2) and superior mesenteric artery (SMA) hemodynamic parameters in neonates during red blood cell (RBC) transfusion. Methods A total of neonates who required RBC transfusion and were admitted to the neonatal intensive care unit between October 2024 and October 2025 were enrolled in this study. Synchronous monitoring of SrSO2 and SMA hemodynamic parameters — including peak systolic velocity (PSV), end-diastolic velocity (EDV), and resistance index (RI) — was performed at eight predefined time points: 1 hour before transfusion (t-1h), mid-transfusion (tm), end of transfusion (te), and 2, 4, 12, 24, and 48 hours after transfusion completion (t2h, t4h, t12h, t24h, and t48h). Spearman correlation, generalized estimating equations (GEE), and cross-lagged correlation analyses were used to examine the associations among the indicators. Results A total of 43 neonates were included, with 26 boys (60.5%). The median gestational age was 31.1 (29.0-36.0) weeks and the median birth weight was 1750 (1255-2600) g. During the observation period, the median PSV ranged from 33.4 to 46.9 cm/s, median EDV from 9.6 to 11.5 cm/s, median RI from 0.73 to 0.77, and median SrSO2 from 49.8% to 56.5%. Correlation analysis revealed a significant negative correlation only at t4h between RI and SrSO2 (rs=-0.52, Padjusted=0.048); no significant correlations were found at other time points (all P>0.05). GEE showed that time had no significant effect on PSV (β=0.003, P=0.992), EDV (β=-0.073, P=0.449), or RI (β=0.002, P=0.324), but had a statistically significant positive effect on SrSO2 (β=0.776, P=0.004). The absolute values of the mean cross-correlation function (CCF) between PSV, EDV, RI and SrSO2 were all small (the highest was 0.151 for PSV at lag-1), indicating no clear lagged relationship. Conclusions During RBC transfusion in neonates, the SMA hemodynamic parameters remain relatively stable, whereas the SrSO2 shows an overall increasing trend. There is no significantly synchronous or lagged correlation between the changes in these two measures, suggesting that macrohemodynamics and microcirculatory oxygenation may be regulated by different mechanisms.