Under new policies people with one DUI conviction that is not too recent will be permitted to entry to Canada with a DUI on a Temporary Resident Permit (Canada TRP DUI) without a fee. People with more than one criminal conviction, whether they are DUIs or other crimes, will still be barred unless they obtain a TRP or a certificate of rehabilitation under the old rules.
You should still plan ahead and learn more about Canada entry requirements for DUI. It is not clear yet how recent or how serious a DUI must be to bar you. You should contact Immigration Canada at the Point of Entry where you plan to enter Canada to determine their interpretation before you go. It used to be that Canada does not allow DUI entry, but that is changing.
For more information on traveling to Canada after a DUI conviction, click here.