Conquistador Cielo is the kind of rarity that race track people term a "freak," a horse who transcends the ordinary rules of the game.

And so it didn't matter that the pedigree experts said he could not possibly win the Belmont Stakes. It didn't matter that his underpinnings are so fragile that his trainer must worry constantly about his physical well-being. It didn't matter that he raced only five days ago. It didn't matter that his regular jockey, Eddie Maple, had been injured Friday and was replaced by Laffit Pincay Jr.

Conquistador Cielo brushed away these doubts as easily as he brushed off his opposition today, and ran away with the $266,200 Belmont Stakes by an astonishing 14 1/2 lengths over Kentucky Derby winner Gato del Sol. Linkage, the favorite, was fourth.

Less than a month ago, Conquistador Cielo was little-known. First he won a minor race at Pimlico; then he won an allowance race here by 11 lengths, and then on Monday he won the Metropolitan Handicap by more than seven lengths, running the fourth-fastest mile in the history of the sport.

His trainer, Woody Stephens, is ordinarily a very cautious horseman, but he decided to take a shot at the Belmont, even though he knew that no offspring of Mr. Prospector had ever won at 1 1/2 miles. His reasoning: "After the Met, I thought he was the best 3-year-old in America."

Maple had ridden him in the Metropolitan Handicap, but he suffered a rib injury in a spill here Friday, forcing Stephens to summon Pincay from California aboard a red-eye flight. The switch didn't matter. Nothing would have stopped Conquistador Cielo today.

He broke from the gate with his customary alertness, as did the colts who were supposed to be his principal rivals, Linkage and Aloma's Ruler, winner of the Preakness. But the other riders didn't want to get into a speed duel with Conquistador Cielo, and they probably were happy when Anemal, a 40-to-1 shot, ran with him for the first quarter mile.

After Anemal dropped back, Bill Shoemaker positioned Linkage within striking distance, but he was pleased that another outsider, High Ascent, rushed up along the rail to challenge the leader. Sitting in third place, Linkage seemed to be in an ideal position. But Pincay knew otherwise.

"The way my horse was running," the jockey said, "I knew he would never get beat. He was relaxing and he gave me so much confidence that he was going to win."

Conquistador Cielo had set an honest pace--running a half mile in 47 1/5 seconds, six furlongs in 1:12 and a mile in 1:37 2/5--when Linkage attempted to challenge him and Gato del Sol also began to accelerate.

But the front-runner never gave his supporters in the crowd of 45,128 a moment's worry, never gave any indication of the supposed shortcomings of his pedigree. "All I had to do was tap him on the shoulder," Pincay said, and his horse began to pull away with every stride. He finished the mile and one-half in 2:28. 1/5 over a track that was fairly firm despite day-long rains.

Gato del Sol, the runner-up, was four lengths ahead of Illuminate, and Linkage was another 3 3/4 lengths back in fourth place. Aloma's Ruler finished ninth, more than 44 lengths behind.

Conquistador Cielo earned $159,720 for his owner, Henryk deKwiatkowski, and paid $10.20, $7.40 and $6.80 as second choice in the wagering. Gato del Sol returned $8 and $6.40 and Illuminate paid $6.40 to show.

"I never quite ran a horse like this," Pincay said. "He ran just beautiful all the way. When I asked him, he responded. He's a great horse."

After the race, Pincay talked to Maple. "I hope you feel better," he said. "Fortunately, I got the winner. Thank you very much."

Until a month ago, Conquistador Cielo was a colt with more physical problems than accomplishments. He had displayed some potential at Saratoga last summer, but was badly hampered by shin troubles and had to undergo an operation on a small broken bone. He showed promise again in Florida this winter, but was still bothered by the shin, and Stevens now attempted to treat it with a device that sends an electric current through the injured area to speed the healing process.

The same machine had helped Aloma's Ruler, and Conquistador Cielo responded to the treatment. His brilliant victory in the Metropolitan Handicap finally revealed the ability that had been concealed by all his physical problems. After his victory today, that ability seems almost limitless. Bond Suspended for Five Days

Bernard P. Bond, a trainer from Towson, has been suspended for five days for conduct detrimental to the best interests of horse racing, the Maryland Racing Commission announced yesterday.

Bond used "extremely foul and abusive language" on May 31 in stating that the racing stewards at Laurel Race Course were incapable of making proper decisions.