千禧年大奖难题（Millennium Prize Problems），是七个由美国克雷数学研究所（Clay Mathematics Institute,CMI）于2000年5月24日公布的数学难题。根据克雷数学研究所订定的规则，所有难题的解答必须发表在数学期刊上，并经过各方验证，只要通过两年验证期，每解破一题的解答者，会颁发奖金100万美元。

这些难题是呼应1900年德国数学家大卫·希尔伯特在巴黎提出的23个历史性数学难题，经过一百年，许多难题已获得解答。而千禧年大奖难题的破解，极有可能为密码学以及航天、通信等领域带来突破性进展。

The Millennium Prize Problems are seven problems in mathematics that were stated by the Clay Mathematics Institute in 2000. The problems are Birch and Swinnerton-Dyer conjecture, Hodge conjecture, Navier–Stokes existence and smoothness, P versus NP problem, Poincaré conjecture, Riemann hypothesis, and Yang–Mills existence and mass gap. A correct solution to any of the problems results in a US $1M prize (sometimes called a Millennium Prize) being awarded by the institute. The only solved problem is the Poincaré conjecture, which was solved by Grigori Perelman in 2003.