Over 115 people were also injured when the bombers struck a large group of Frontier Constabulary personnel about to go on leave after completing a year-long training course.
The first bomber, who was on a motorcycle, detonated his explosive vest near the main gate of the Frontier Constabulary training centre at Shabqadar, 35 km from Khyber-Pakhtunkhwa capital Peshawar.
The second bomber, who too was on a motorcycle, struck about eight minutes later as security personnel were removing the dead and injured from the spot, witnesses said.
A total of 73 people, most of them Frontier Constabulary personnel, were killed, a police official was quoted as saying by state-run PTV.
Over 115 injured people were taken to hospitals in Shabqadar and Peshawar.
Tehrik-e-Taliban Pakistan spokesman Ahsanullah Ahsan, speaking to reporters in northwest Pakistan on phone from an undisclosed location, claimed the attack was the "first revenge" for the killing of bin Laden in a US raid in the garrison city of Abbottabad on May 2.
He warned the militants would carry out "bigger attacks".
Police officials said they feared the death toll could rise. The condition of 40 injured at the Lady Reading Hospital in Peshawar was described by officials as serious.
The Frontier Constabulary personnel had recently completed their year-long training and passed out during a parade held on May 5, officials said.
They were going home for a 10-day leave when the bombers struck. Most of the personnel, who were in plainclothes, were sitting in mini buses when the bombers struck.
The powerful blasts destroyed about 20 shops and a dozen vehicles. At least five civilians were among the dead.
Footage on television showed rucksacks, footwear and other belongings laying scattered amidst pools of blood at the site of the attack.