Objective To explore the association between screen time and infant language delay,in order to provide evidence for the prevention of language delay in infants. Methods A randomized sampling method was used to select 112 infants aged 18 to 46 months diagnosed with language delay in Shanghai Children's Hospital as case group from November 2017 to August 2018,meantime 66 healthy children matched by gender and age were selected as control group. A self-designed questionnaire on infant language delay and screen time was used to conduct this survey. Results There were no statistically significant differences on children's age,parents' occupation and whether parents were only child or not(P＞0.05),while parents of control group had older age and higher educational level(P＜0.05). However,mothers in case group had spent more time with their children on weekdays than mothers in normal group(t=-2.281,P=0.020). And the average screen time in case group was significantly longer than that in control group(t=-3.224,P=0.002). The content of screen in children was mainly animation,but the proportion of normal children watching science films was slightly higher than that of case group(χ²=11.558,P=0.009). In terms of limiting the screen time and having a rest after screen time more than 30 minutes,parents of normal children performed better than that of case group(χ²=6.962,11.034, P＜0.05). Parents in case group allowed their kids to use video products more frequently than parents in control group(χ²=11.752,P=0.003). Mothers from case group spent more total time and leisure time on screen than mothers from control group(t=-2.920,-2.145,P<0.05). After controlling for confounding factors,it was found that children's screen time was an important factor affecting language development. For every one hour increase in children's screen time,the language development quotient decreased by 1.626. Conclusions Screen time is an important factor affecting children's language development. It is suggested to limit children's screen time every day in the family and parents should set an example to increase face-to-face emotional communication opportunities,thereby promoting children's early development.