Forma interrogativa de "They visit our last year"

Did they...?

In fact the initial sentence should be "They visited us last year."
Then, on Marcio suggestion "Did they visit us... (visit- the verb doesn´t take the "ed" in the end here, because of the particle '"Did").

Are they visit last year?

No.

I agree to "PPAULO" about the initial sentence to be incorrect:

- They visit our last year. (Incorrect)
- They visited us last year.(correct)

Therefore, I believe the correct interrogative form would be: Did they visit us last year?

So we think alike, with (...) I meant the rest of the sentence was like you pointed out.
Indeed I expanded Marcio answer only because we could have English learners that might not have met the topic (or the information) of DID/DO not supressing the "ed" of verbs.