The Italian coach spent two years at the Parc des Princes before departing for Real Madrid in 2013, winning one Ligue 1 title during his time at the club.
Ancelotti claims that PSG have evolved even further since he was in charge, particularly on the back of signing Kylian Mbappe and Neymar for a combined £364m during another busy summer transfer window.
"With Neymar and Mbappe, Paris are looking for an identity," he told Le Figaro. "At Bayern, it's clear. For years, the line has been drawn, the identity is clear, which is not yet the case at PSG. But Paris are already at the level of the best. When you buy players at this price and this level, you have to have time and they have to enter the mindset of the team. That is their challenge.
"[The feeling for me is one of] excitement - I will find a Paris Saint-Germain which has changed a lot since I left in 2013. The club has improved and has more experience after a lot of investment. Now it's a big club. I am happy to see the Parc des Princes, the supporters and players like Thiago Silva, [Adrien] Rabiot, [Thiago] Motta, [Marco] Verratti, [Javier] Pastore.
"We had a good relationship, they missed me. I also keep in touch with the president (Nasser Al-Khelaifi). I have good memories of my time there. I helped the club to change mentality and PSG managed to grow a little more afterwards. Even if we had problems following my departure for Real Madrid, when I think of Paris, I am happy."
PSG have lost just once in their last 43 European outings on home soil, but Bayern have won on each of their last three visits to France.