Bologna

Go by train, easy. Look up times and prices, and buy tickets in advance if you want to, on www.trenitalia.com
You will have to enter the placenames in Italian, the station in Florence is called "Firenze S. M. Novella". Prices start at €13 for advanced bookings, going up to €29 if you buy a ticket on the day of travel. There are 3 trains per hour.

High speed train. 37 minutes.
www.trenitalia.com
Bologna can be visited in a day. Whether you wish to stay there overnight or not is up to you. You could also go in the morning, leave your luggage at the station while you visit, and in the evening proceed by train to Milan (after retrieving your luggage).

Oh yay great! Thank you. Any recommended hotel in Bologna? Which part should I stay ? Prefer dining and shopping. Want to go to the hermes store in Bologna. Is it easy to reach?

The main high-end shopping area is near Piazza Cavour. The map your hotel gives you will show you the location, it is one of the major bus transfer points in the city.

I like Hotel Metropolitan.

Do you mean I can store my luggage at Bologna train station? Please guide me.

Yes. You can leave your luggage at the station's luggage storage while you visit the city. Look for the signs to DEPOSITO BAGAGLI (baggage depot).

http://www.grandistazioni.it/cms/v/index.jsp?vgnextoid=0e08d8a55b4eb110VgnVCM1000003f16f90aRCRD

Thank you so much!

Cracking my head! Not knowing which option is better for me.
Option one:
From Florence , travel to Bologna with luggage, check in hotel metropolitan. Stay for a night and next noon travel to Milan.
Option Two:
From Florence , travel to Bologna without luggage, after a day of eating, shopping, sightseeing, travel back to Florence. Stay in Florence for a night and next day, travel to Milan.
I knew I can deposit my luggage at Bologna but how safe is it? And is there a charge? Won't it be better to choose either one of my option?

If you already have a hotel in Florence that you are staying at, it might be better to just stay there and go to Bologna for the day, and come back to Florence at night. That way you don't have to pack, move to a new hotel, unpack for a night, then pack and move in the morning. Go to Milan from Florence.

In other words, option 2!

Thank you Charlotte!

What are the must go places in Bologna?
Which are the restaurant that I should not miss?
And the gelato?

I was really impressed by the old University. Mostly I just enjoyed walking through the historic center.

Any idea if it close from the train station to metropolitan hotel? Or how much does it cost for the taxi ride from station to hotel?

What is the Bologna station name?

Guide books list several things in Bologna, including the food and the architecture.

Bologna Centrale is the main central station in Bologna, located on the north side of the centre, beyond most of the university.

Option one or two is up to you.
There is also option 3: leave Florence early morning. Store luggage at Bologna station. Visit Bologna for the day. At the end of the day, retrieve your luggage and take an evening train to Milan. This is the option I would choose. You don't need a night in Bologna and with this option you save the train fare to back track to Florence (50 euro round trip).
The Metropoilitan hotel is 15 min walk from the station.
The luggage storage at station is very safe. It's not a locker cabinet. It's a manned cloak room and you need photo ID to leave and retrieve your luggage. Yes there in an hourly charge per bag to store luggage. I gave you the link above. Go there and check the prices. Make sure you retrieve your luggage before closing time.

Thank u so much!

Any good recommendations for Milan hotel? I like to stay in Milan center area.But not too X

option 4 is to stay 2 nites in Bologna. 1 to see the city, the 2nd to use it as a base to visit Parma and Modena (or some of the other towns in the area). These 2 are easily reached by train.