If you'd like to book that journey with Rail Europe, you need to search for Paris to Bruxelles Midi.

Eurostar doesn't stop at Bruxelles-Central and you won't be able to book if you do search for Bruxelles-Central (even if you do get a timetable). But Rail Europe will let you book it when changing the arrival station to Bruxelles Midi.

Thanks for the help!

Now i realize Eurail is not good pass . I check and they shows so many  train schedule are all fully book.

And I check trainline there are so available tickets.

On what date do you want to travel from Paris to Brussels?

Eurostar is one of the few trains with a quota for pass holders. For Paris to Brussels though there are alternatives though.

yes, I have to check Eurostar.

funny thing is the eurostar website shows no seat for the morning until late afteroon.

I check Trianline , they have seats for the morning .

Since Eurail has so much limitation I would have book direct…

Eurostar website is more reliable than Trainline or any third party! Please give us a travel date and we'll have a look.

You can go via Lille, Maubeuge, etc. anyway -> this route is not an issue at all.

30 Apr, Morning 8-10am . 7 pax.

If you could advise any other routes - Bruxelles Midi to Den Haag Central for 2 Apr ? I also got hard time getting the direct routes?

There are passholder seats left on the 08:24 and 10:24 services (+ later ones), not in between. You shouldn't wait to book.

Eurostar trains are quite expensive : 7 x 27€ for this train. It adds up quickly! There are ways to save money though.

For example you could travel via Lille for 7 x 10€ : updating.

- TGV Paris-Nord - Lille-Flandres 08:45 - 09:48 10€ per person

- TER Lille-Flandres - Tournai 10:08 - 10:36

- IC Tournai - Bruxelles-Midi (or Central) 10:45 - 11:48

Or fully free via Maubeuge (other departure at 10:32) :

- TER Paris-Nord - Maubeuge 07:17 - 09:18

- R Maubeuge - Charleroi-Central 09:43 - 10:38

- IC Charleroi-Central - Bruxelles-Midi 10:53 - 11:45

For Brussels - Den Haag you mean 2nd May, right? Anyway take the hourly reservation-free IC Direct to Rotterdam* and change to a very frequent train to Den Haag.

*board in Midi station for more seats, especially as you're a large group.

Thanks for the help!

For Brussels - Den Haag,  I traveling on  2nd Apr.

Thanks for the tips to Rotterdam. One questions, my Eurail pass I can use for Netherlands domestic train or subway?

Domestic trains yes. Subways, trams or buses no.