The Team USA star had to work for it though, pushed all the way to the line by China's ZHOU Zhaoqian who was just 0.16 behind McFadden.
Merle Menje from Germany claimed the third qualifying spot in 3:36.46.
The women's 1500m T54 final will take place on Tuesday 31 August at 20:56 JST.
McFadden is the double reigning champion at this distance and is aiming for a golden threepeat which would be her eight Paralympic gold medal and a 20th overall.
Add USA teammate Susannah Scaroni to the mix and we have an exciting race on our hands tomorrow.
McFadden has won silver and a bronze (In the 5000m) already here at the Tokyo 2020 Paralympics, and is going all out to complete the set with gold.
When is Tatyana McFadden competing next at Tokyo 2020 Paralympics in 2021?
Tatyana McFadden will be back on track at the Tokyo 2020 Paralympics on Tuesday August 31 from 20:56 JST in the women's 1500m T54 final.
Her two other events coming up are:
Women's 400m T54 - Thursday 2 September with heats starting at 12:42pm and the final at 19:40pm.
Women's marathon T54 - Sunday 5 September 6:40.