25-year-old Julie Lynn Kindstrand Nelson -- known professionally as Julz Lynn -- went public with the accusations on Tuesday ... saying Hendrix "used his position of influence to pursue his own sexual ambitions, which included luring me to have sex with him" ... beginning when he was in his early 30s.

Julz told espnW ... Hendrix first met her at a skate park in 2006 and convinced her to come to his apartment for "sex lessons." She also claims Hendrix masturbated in front of her and took naked videos of her while she was underage.

Julz has reached out to the Costa Mesa Police Department in CA -- and has also called for other possible victims of Hendrix to come forward.

She's also pointing the finger at skate officials -- saying the International Olympic Committee and USOC "never cared to pay any attention or look into illegal inappropriate interactions with many underage athletes."

Julz says her experience with Hendrix took her innocence and destroyed her career ... and now she's "in the process of getting my life back together."

Hendrix -- now 45 -- won five X Games medals during his career ... and has been a TV commentator for big events like Dew Tour and X Games. He's also on the USA Skateboarding executive committee.