Phelps, a 14-time Olympic champion who took a record eight gold medals at the 2008 Beijing Games, led from start to finish to win in 1min, 54.79secs with China's Wu Peng second in 1:56.71 and American Neil Caskey third in 1:59.82.
With the triumph, Phelps erased a pool record that had been his first world record - a mark of 1:54.92 in 2001 at age 15. Phelps went on to lower that world record and win his first world title in the event last in 2001.
"I wanted the pool record to stand just because that was my first world record," Phelps said. "This is kind of where everything started going. This is a great pool for me."Phelps won the 100 butterfly on Friday and the 400 individual medley on Saturday at the meet, but had not been happy with his showing at the meet. "Over the weekend I hadn't had that great of swims," Phelps said. "Hopefully going into trials we can fix that and be ready like this every day."
Megan Romano swam the fastest time in the world this year to win the women's 100 backstroke in 1:00.19 and Brendan Hansen, who helped Phelps win gold in the 2008 Olympic 400 medley relay, won the men's 100 backstroke in 1:01.16.