Milan to Venice train

You will be taking a Malpensa express train from the Malpensa airport to the Milano Centrale station (trains are operated by the Trenord company). Make sure you take the train to Milano Centrale and not Milano Cadorna station. Schedule below:
http://www.malpensaexpress.it/en/
There are also buses that can take you from the airport to Milano Centrale. It takes about the same time either way, although buses are affected by traffic.

Once at Milano Centrale you will take a Trenitalia train to Venezia Santa Lucia. Schedules below.
http://www.trenitalia.com/
The fastest trains are those called Freccia...

You can buy tickets for the entire trip (both trains) at the airport station.

It is possible to purchase online ahead of time, but since your airplane arrival may be subject to delays because of weather, baggage claim, immigration, etc. it is safer to buy them on the spot when you are at the airport station. Trains are never sold out, at most you have to wait for the next one an hour later but it has never happened to me.

You will need to make and pay for reservations on the fast (Freccia or InterCity) train from Milano Centrale to Venezia Santa Lucia >IF< you are using a rail pass.

Otherwise, when you buy the ticket as Roberto showed above, the reservation is included and you will have an assigned seat.

I am also flying to Milan and traveling by train to Venice from the Milan airport. I have already purchased "Eurail global pass" .
Do I need to make a reservation ahead of time since I have purchased the pass?

@Jamie, Its always best to start a new thread for your question rather than piggy back on another's. The OP may be getting email notification of answers to their questions, and this will pester them somewhat if you post your own question on top of theirs.
You will need to buy a ticket (12 euro) from Malpensa to Milano Centrale as your pass is not valid on that train. At the very least, you will need to buy a reservation for 10 euro before boarding the train from Milan Centrale to Venice.

If you want to take a chance on timing and can book 120 days ahead, you can get a Milano Centrale-Venezia Santa Lucia ticket for €9. I would allow plenty of time for possible delays, however, since if you miss that train you will need to buy a full-fare ticket.

To all thanks for the reply and the information .
It will be well used.