Although the United States (US) have been monitoring the autism spectrum disorder (ASD) prevalence, whether the prevalence has continued to increase, decrease, fluctuate or reached a stable level remained unclear during the COVID-19 pandemic. We have requested the 2016–2021 National Survey of Children’s Health (NSCH) data in the United States to estimate weighted ASD prevalence and assess linearity/nonlinearity in the time trend. We did not observe linear or nonlinear trends of the ASD prevalence during the 2016–2021 periods. The current ASD prevalence experienced a 0.3% drop from 2019 to 2020 but a 0.3% uptick in 2021, suggesting a stable trend during the COVID-19 pandemic. Our findings shed lights on the need for the modified strategy of monitor ASD prevalence during the COVID-19 era.