The delegation moves on to co-hosts Ukraine on Thursday.
Poland and Ukraine were awarded to host the major European soccer championship in 2007, but in January UEFA expressed its dissatisfaction with the progress the countries had made getting ready for the event.
"We will meet with the countries' leaders and hold discussions with all the relevant bodies in charge of the preparations for UEFA Euro 2012, in order to take stock of the current situation within the two countries," the website quoted Platini as saying before the trip.
Speaking in January about progress by Ukraine and Poland in meeting UEFA standards and deadlines, Platini said, "I have the distinct feeling that the next four to six months will be crucial."
The UEFA president met Wednesday with Polish Prime Minister Donald Tusk and President Lech Kaczynski and is set for talks Thursday with Ukrainian Prime Minister Yulia Tymoshenko and President Viktor Yushchenko.
Platini said the results of the meetings and inspections would go into a report to be discussed at a UEFA meeting in the fall.
"A report will then be given to the UEFA Executive Committee in order that they can fully review the situation in the two countries at our next meeting on 25 and 26 September in Bordeaux," Platini said.
Before the Euro 2008 final last weekend, he denied that there were plans to move the tournament to another country. Media reports have suggested Scotland was eager to host the event in case Poland and Ukraine drop out, while Italy and Spain have also been mentioned as possible replacements.
