Combo Tickets for Beijing Zoo

Yes, you can buy Zoo + Aquarium Combo Ticket. The ticket service counters of aquarium provide such tickets. Don't worry.
For adult, the ticket fare is CNY 160. For child above 3.9 feet (1.2 meters), the fare is CNY 75. Children below 3.9 feet (1.2 meters) are free of charge.

So the 160 RMB is plus the Zoo, but I thought the Aquarium was inside the park, so I had to pay Zoo tickets to get to the Aquarium?

The fact is that the Aquarium has separate entrance (at the North Gate of the zoo). You can visit it alone or have a combo ticket to see both of them.

Ahh okay thank you so much for the info :)

Oh wait then, I can't find any single Price entry on the Aquarium website, only the 160 RMB. So what is the single entrance Price only for the Aquarium?

The single entrance price for the Aquarium is CNY 160. Considering the combo ticket costs the same. It is suggested to have one so that you can see both sites.

I am a little confused now you write the North Exit at the Zoo, but at this website for the Aquarium it says South Exit?

I've checked on the official website of the Aquarium. Its separte ticket counter is close to the North 4th Gate of the Zoo.

And I read that TCG says that Exit A of the metro station is close to the South Gate of the zoo, but your destination is at the North Gate, so you still need to walk there. Their printing card is quite clear.