Nearly 1,600 parents lined up yesterday some arriving as much as 11 hours early -- to enroll their children in the Prince George's County magnet school program, which enters its second year this fall.

The large turnout at three county schools came on the first day of registration for five new programs, surprised and pleased school officials. "It's amazing. I never thought there would be anything like this," said school board Chairman Paul Shelby.

The county will enroll 1,400 students in the new programs, which will offer special courses, including foreign languages, math and science, to draw white families to predominantly black schools. The magnet school program was introduced this school year in an effort to resolve a 13-year-old desegregation lawsuit. The county has operated a busing plan during that time, but enrollment at dozens of schools has remained predominantly black.

The programs have been installed at 12 schools this year, and will be available at 30 the 1986-87 school year.

Students are accepted according to racial guidelines, so there may be openings still available after 1,400 applications have been accepted. Parents may apply for openings at meetings tonight, open houses at the schools May 31 and by mail.

Barbara Sollner-Webb waited in line from 8:20 a.m. to 7 p.m. at Eleanor Roosevelt High School in Greenbelt to enroll her 5-year-old daughter Lisa in a science and math school. "It's where we want to be," she said.

Carla Arnold, one of about 40 parents who spent the day camping out in lawn chairs, said she was taking her daughter Allison Anne out of private school to put her in a school for gifted children. "We feel she'll get as much as she does now and more."

School spokesman Brian J. Porter said the enthusiastic response indicated "early interest" and faith in the program. "Everyone's signing up for the programs sight unseen," he said. "They are believers."

At Roosevelt High School, nearly 1,000 parents applied, with lines winding through the school corridors. About 600 parents showed up at two other schools.

This year 12 magnet schools offer day care and courses for talented students. Next year there will be programs in humanities and social sciences, science and math, foreign language immersion, Montessori schools and "traditional academy" programs.

In addition to the magnet program, the Prince George's County school system provides extra "compensatory education" funding to some predominantly black schools because officials say they cannot be desegregated.