Tracy Caulkins set her fourth and fifth American records of the AAU national swimming championships tonight and extended her unbeaten streak in national competition finals to 15 races.

The 16-year-old from Nashville, who won the 1978 Sullivan Award as the notion's outstanding amateur athlete, broke her own 200-yard individual medley mark of 1:59.33 by streaking to a 2:57.86.

Joan Pennington of Austin, Tex., was second, 10 yards behind, in 2:02.01.

Caulkins also set an American mark in the 100-yard freestyle when she led off Nashville's relay with a 49.03 to break Cynthia Woodhead's mark of 49.39 set earlier in the night. The Nashville relay team also set an American record 3:20.51.

Caulkins has won the 100-yard breast stroke, the 500-yard freestyle and the 400-yard individual medley, all in American record times.

Three other U.S marks fell tonight in the championships that also served as qualifying for the Pan American Games teams. Eighteen records have been broken at this meet.

Cynthia Woodhead started the record spree, topping the 100-yard freestyle mark of 49.55 set by Jill Sterkel. Woodhead, flashed to a 49.39 with Sterkel second in 49.48.

Woodhead, 15, of Riverside, Calif., has setr three American marks and won two events during the four days of these championships at East Los Angeles Colllege.

Kim, Linehan, 16, of Sarasota, Fla., got the 14th U.S mark moments later in the 1,650-yard freestyle. Linhan, a 5-foot-1, 104-pound high school junior, smashed Woodhead's mark of 15:5with a 15:49.1. Jennifer Hooker was second in 15:51.46.

Linehan, referring to a late charge by Hooker at 1,300-yard mark, said, "I was little worried because the exact same thing happened to me last year when Sippy (Woodhead) and Jennifer caught up with me during the last 500 yards after I had a large lead."

In the men's 1,650-freestyle Brian Goodell of Mission Viejo, Calif., crushed the mark he set two weeks ago at the NCAA championships with a 14:17.27.