Officials say 45-year-old Gary Hutt is being charged with 200 counts of sexual abuse of children for possessing and distributing child pornography.
Hutt started coaching at Berks East Gymnastics in Parker Ford, Chester County, in January.
He has since been fired, officials confirm.
Thanks to the National Center for Missing and Exploited Children, investigators received a tip that helped lead to Hutt's arrest.
Detectives say they found thousands of images and videos from the past 17 years.
If you have any pertinent information about Hutt, you are asked to contact Chester County detectives.