As of May 1, 2010 all foreigners holding a valid US visa will be eligible to enter to Mexico from any port of entry without a Mexican visa, regardless of their nationality. This will apply to tourists, businessmen, entrepreneurs and visitors on transit.
--摘自墨西哥驻底特律领事馆网站
注意,你的护照必须有半年以上有效期(也是国内访客入境美国的规定)。