PINE RIDGE, S.D. (AP) _ When 35 teen-agers from across the nation arrived at the Sioux reservation here, they knew little about Indian culture, but after a week, they found a lot to admire and sympathized with Indian problems.

''When I found out I was going to a reservation, I thought about tepees and open range,'' said Gary Levenston of Coral Springs, Fla., who participated in the program that ended Friday. ''I'm surprised by similarities between their culture and mine. A lot of their beliefs and values are ones everybody should follow.''

Indian youths, too, said they benefited from the exchange, sponsored by the non-profit National Conference of Christians and Jews.

''I've been off the reservation, but not enough to stay and talk with people and learn about different cultures,'' said Mia Whirlwind Horse of nearby Wanblee. ''It's really been valuable. I've got new friends. I learned to open up to people.''

The conference at the Pine Ridge Indian Reservation was designed to help students not only learn to deal with universal problems of young people, but also to teach them to be leaders who can work with people from different racial, religious and cultural backgrounds, said organizer Rose Marie Ohm.

The organization holds similar conferences elsewhere, but the Pine Ridge event gave the urban teen-agers a good look at Indian culture on the isolated reservation, Ohm said.

''The best impact we've made is when we take them to the environment,'' Ohm said. ''That's why NCCJ invested money and time and effort to bring them here. We do not want just another conference where we just talk about it.''

The reservation is a region of rolling hills topped with pine trees in southwestern South Dakota. Its territory includes Shannon County, one of the poorest in the nation.

Ohm said Indian students weren't eager to join the program at first, but 15 to 20 trickled in as the conference progressed.

''We had to answer a lot of questions about our coming here,'' she said. ''The trust level has been bridged.''

The non-Indian teen-agers, mostly from urban areas, visited a Sioux powwow for Indian military veterans on the first full day of the conference. Ohm said they also met with elderly spiritual leader Frank Fools Crow and former American Indian Movement leader Dennis Banks, who now is working on economic development and drug and alcohol abuse programs on the reservation.

Banks showed the teen-agers a lot about Indian tradition and explained the Indians' effort to regain ownership of the nearby Black Hills region, which the Sioux believe was taken from them illegally more than a century ago after gold was discovered.

The students discussed problems of racial prejudice, friendships, dating and family relationships. They selected prejudice, alcohol and drug abuse, teen-age pregnancy, apathy in schools and suicide as the top problems facing young people, Ohm said.

Levenston said his conversations with Indian students showed him the reservation has some serious problems, such as alcohol and drug abuse and violence. ''I had no idea it was this bad,'' he said.

He also said he's gained a new understanding of the Sioux effort to regain lost land and the need to improve the reservation economy.

''They have the right to be self-sufficient. We should help them,'' Levenston said. ''They don't want financial help. They want their land back.''

Indian student Darcy Redday of Sisseton, S.D., said she wanted to return home when she first arrived at the conference, but she learned a lot and had fun explaining her culture to other students.

Redday said the conference helped her overcome her fear of speaking out and being a leader. ''It helped me build up courage, so when I go home I can do that.''

Abby Mauk of Minneapolis said she didn't want the week to end.

''I've never made friends so fast,'' Mauk said. ''It's my first absolutely colorblind experience. It's like we all met in the dark and didn't know each others' backgrounds.''