Although reports have shown an association between coronavirus disease 2019 (COVID-19) and a reduction in male semen parameters, no population big-data analyses have been verified. This ecological comparative study aimed to explore the effects of the COVID-19 pandemic on semen quality. This ecological comparison study was based on the nationwide loosening of COVID-19 curbs in China on 2022-12-07, 1 month after which, an 89% infection rate was reported in Henan Province, China. We compared semen quality and serum hormone levels from 2023-01-07 to 4-30 and 2022-01-07 to 4-30 at the Reproductive Center of Henan Provincial People’s Hospital. Our results indicated a significant decrease in semen volume ( P<0.0001), sperm concentration ( P=0.0004), total sperm count ( P<0.0001), progressive motility ( P<0.0001), and nonprogressive motility ( P<0.0001) after the nationwide loosening of COVID-19 curbs. The effects on semen volume and total sperm count lasted for a long time. An increase in the rate of sperm neck defects was observed ( P<0.0001). Infection also caused hormone disruption in prolactin ( P<0.0001), testosterone ( P=0.0220), sex hormone-binding globulin ( P<0.0001), and free testosterone index ( P=0.0126), and an increase in estrogen ( P<0.0001), osteocalcin ( P<0.0001), and 25-OH-VD ( P<0.0001). The present study revealed that mild COVID-19 appeared to have a detrimental effect on semen parameters.