It happened in the 9000 block of Antoine at Fairview Forest Drive at around 1 p.m. on Monday.
According to investigators, the woman may have lunged in front of the 18-wheeler before getting hit. They said she was dragged about 100 feet from where she was hit.
The Harris County Sheriff's Office says the northbound lanes of Antoine are shut down as deputies continue their investigation. Investigators are currently reviewing video from the 18-wheeler's camera.
The incident remains under investigation.