He said the tests ignored differences in business models, but added it was right the government try to save banks.
The results of the stress tests were due to be published on Monday, but have been delayed until Thursday.
Referring to Berkshire Hathaway's holdings in Wells Fargo, US Bancorp and SunTrust Banks, he said, "I think I know their future, frankly, better than somebody that comes in to take a look. They may be using more of a checklist-type approach."
Buffett was speaking at a news conference with Berkshire Hathaway vice-chairman Charlie Munger. They hosted a record 35,000 people at the Omaha, Nebraska-based firm's annual meeting on 2 May before the conference.
Munger added, "This 'one size fits all' reasoning in the case of bank stress tests is very likely to be done poorly."
However Buffett, who is the world's second-richest man, endorsed government efforts to stabilise the financial system. "There is no reason ever in the United States to have a run on the bank," he said. "The United States government has demonstrated that whatever it takes is what is going to get done, and they are right to do so."
Buffett also criticised the strategy of companies buying back their own shares. "Most of the repurchasing in recent years was foolish," he said, adding that companies tended to pay too much and the practice almost always destroyed value.
Buffett also lambasted bankers, insurers and regulators for being blind to the possibility home prices could fall, and said their shortcomings caused the worst recession in half a century.
Buffett and Munger said Wall Street sold subprime mortgage ''sewage,'' and blamed the media and regulators for missing the danger.
''I think that virtually everybody associated with the financial world contributed to it,'' Buffett said of the crisis. ''Some of it stemmed from greed, some from stupidity, and some from people saying the other guy was doing it.''
Home foreclosures have advanced to a record, US unemployment rose to its highest in 25 years and Berkshire shares plunged about 30 per cent since shareholders gathered at Omaha's Qwest Center arena last year. The US government and the Federal Reserve have spent, lent or committed $12.8 trillion to shore up the economy.