To evaluate the efficacy of biofeedback and electrical stimulation-assisted pelvic floor muscle training (PFMT) between women with mild and moderate to severe stress urinary incontinence (SUI). This retrospective cohort study was conducted at a single center from 2014 to 2021. We included 57 patients with urodynamically proven SUI who underwent a biofeedback and electrical stimulation-assisted PFMT. They were categorized into mild and moderate to severe SUI. One-hour pad test from 2 to 10 g was defined as mild SUI, and ≥11 g was defined as moderate to severe SUI. Fifty-seven patients were reviewed during the study period. Incontinence-related symptoms of distress, including the UDI-6, ISI, and VAS, all significantly improved in the mild SUI group (p = 0.001, p = 0.001 and p = 0.010, respectively), while only UDI-6 and VAS statistically improved in the moderate to severe SUI group (p = 0.027 and p = 0.010, respectively). There was significant improvement in IIQ-7 in the mild SUI group during serial treatments, but only in Session 6 in the moderate to severe SUI group. After 18 sessions of treatment, the UDI-6, ISI, and IIQ-7 scores showed significantly greater improvements in the mild SUI group compared to the moderate to severe SUI group (p = 0.003, p = 0.025, and p = 0.002, respectively). Although biofeedback and electrical stimulation-assisted PFMT is an effective treatment option for SUI, it is more beneficial for patients with mild SUI and a 1-h pad weight ≤ 10 g urine leak.