The woman was struck at 11:51 a.m. by northbound train No. 143 at Main Street, Caltrain spokeswoman Christine Dunn said.
The woman survived the accident and was taken by ambulance to a hospital, Dunn said.
The train, which had 245 passengers onboard, stopped at the scene, but resumed operation once the scene was cleared shortly after 1 p.m., according to Dunn.
Southbound train No. 142 also stopped as a result of the accident and was about 43 minutes late to its destination, she said.