Although coronavirus disease 19 (COVID-19) was reported to involve with multiple organs, COVID-19 reports focusing on urinary system mostly evaluated the association between lower urinary tract symptoms and COVID-19 using questionnaire score. In this study, sonography video urodynamic studies was first conducted to explore the effects of COVID-19 on contractility of bladder detrusor of patients with benign prostate hyperplasia (BPH). Clinical data was respectively reviewed and compared between BPH patients with previous COVID-19 infection (COVID-19 group) and without previous COVID-19 (non-COVID-19 group). The incidence of detrusor underactivity (DU) was compared between 2 groups. Comparison of age and noninvasive parameters was conducted between BPH patients with DU and without DU in COVID-19 group. Correlation coefficient between noninvasive parameters and detrusor contractility was determined and receiver operating characteristic curve of noninvasive parameters was used to choose the most appropriate cutoff for detection of DU in COVID-19 group. Beside a significant increase in the incidence of DU in BPH patients of COVID-19 group, a lower detrusor contractility and a greater bladder wall thick was detected compared to that of patients in non-COVID-19 group. Post-voiding residual urine was found to have a linear correlation with detrusor contractility in COVID-19 group. It was suggested that COVID-19 infection would further exacerbate impairment of detrusor previously resulted from bladder outlet obstruction in BPH patients. DU may be a urodynamic characteristic of long-COVID.