"I've been very impressed," Daley said, calling the system safe, clean and friendly.
China's capitol city opened two new subway lines and an airport rail link for the games, and the Olympics are a big test of the already crowded public transportation system. Passengers on the three new routes are expected to top more than 1 million daily during the games.
Transportation is a key component of Chicago's bid for the 2016 Summer Games. It's among the areas the city must address because Olympic officials already have questioned its $27 billion estimate for highway and transit projects.
Along with Chicago, the other 2016 finalists are Madrid, Spain; Rio de Janeiro, Brazil; and Tokyo.
Daley is part of a Chicago contingent of more than a dozen people at the Olympics, the only chance for local organizers to see a Games before the International Olympic Committee chooses the 2016 host next year.
Daley said Chicago's infrastructure could be drastically improved if the Chicago Transit Authority used newer rail cars similar to those in Beijing.
"If you can get a modern car built on the old structure, I think you can. I think we can. If you can put a man on the moon then we can really fix this up," he said.
But Daley said upgrading an aging public transportation system to be as nice as the one in Beijing isn't cheap and finding the money to do it is difficult.
"No one can spend this much money. I mean, no one can spend it. I don t care. What country can spend this much money," he said.