For H-shaped gate Double Silicon-On-Insulator (DSOI) NMOS devices, a difference in Total Ionizing Dose (TID) response has been observed with varying channel widths. Devices with wider channels exhibit more significant degradation in electrical parameters. By studying the trap charge density using the Subthreshold Current technique and Direct Current-Voltage technique, the results indicate a positive correlation between channel width and oxide trap charge density, while the interface trap charge density decreases as channel width increases. The variation in the electric field among devices with different channel widths under TG bias is identified as the primary cause of the different radiation-induced oxide trap charge densities. Additionally, the accumulation of oxide trap charge, which forms an electrostatic barrier, influences the generation of interface trap charges.