Hi there
I am in the process of upgrading power to 200 amp in my house. The house receives power from a pole on the property. There is a 200 amp main disconnect (pullout fuse box) on the pole just beneath the meter. I've installed a new 200 amp breaker box in the basement (about 20' from the pole) and pulled 3 3/3/4 awg aluminum wires from main disconnect on the pole to the breaker box in a pvc conduit. My question now is how to ground the system? I understand that the grounding should be via grounding wire and rod buried either near the breaker box or the main disconnect. But do I also need to extend a grounding wire from the breaker box to the main disconnect on the pole?
Thanks in advance for your answers!

The neutral and equipment ground are connected at the meter/disconnect on the pole, and a #6 copper wire needs to connect to at least one ground rod, check local codes, some require at least two rods.

The feeder from the meter/disconnect on the pole to the panel in the home needs to be 4 wire, 2 hots, 1 neutral. And 1 equipment ground. The neutral in the panel does not get connected to the equipment ground.

Your feeder size is "3 3/3/4 awg aluminum wires "? Not sure what that is. A 200 amp residential service needs a min of #4/0 aluminum. If you use a 4 wire #4/0 URD cable, it will come with the proper size neutral and equipment ground.

Thank you for the answer. You clarified all the questions in my mind.

Unfortunately you needed to pull 4 wires. Your breaker box in the house is effectively a sub panel as a result of the main breaker on the pole. Your will need separate grounding and neutral buss' in your house panel, with the neutral NOT bonded to the box... and yes you will also need a grounding rod.

Update:
This is what is printed on the wires.
Hot wires: Southwire (UL) KCMI AL USE 2 95 MILS XLP insulation... 600 volts
Neutral: Southwire (UL) AWG 4/0 AL Type USE 2

Thank you Missouri!

The cable specs you gave shows three wire, need four wires total.