2017–18 Cymru Alliance
The 2017–18 Cymru Alliance is the 28th season of the top football league in North Wales. Mirroring its South Wales counterpart the Welsh Football League Division One, the 16-team division forms half of the second tier of the Welsh football league system and falls one level below the nationwide Welsh Premier League. The season began 12 August 2017 and is scheduled to conclude on 31 March 2018.
Teams
were champions in the previous season and were promoted to the 2017–18 Welsh Premier League; they were replaced by both relegated teams from the 2016–17 Welsh Premier League, Airbus UK Broughton and Rhyl.The bottom four teams from the previous season, Llanfair United, Mold Alexandra, Conwy Borough and Buckley Town, were all relegated to various third-tier district leagues for 2017–18. Three teams were successful in the 2016–17 Welsh third-tier leagues and were promoted in their place: Llandudno Junction, Queens Park and Rhayader Town.
On 27 July 2017, Rhayader Town withdrew from the league, citing that their players were unwilling to commit to the extra travelling involved with promotion. There was no replacement team - the league continued with 15 teams for this season only, playing 28 games each.
Stadia and locations
| Team | Location | Stadium |
| Airbus UK Broughton | Broughton | The Airfield |
| Caernarfon Town | Caernarfon | The Oval |
| Caersws | Caersws | Recreation Ground |
| Denbigh Town | Denbigh | Central Park |
| Flint Town United | Flint | Cae-y-Castell |
| Gresford Athletic | Gresford | Clappers Lane |
| Guilsfield | Guilsfield | Guilsfield Community Centre |
| Holyhead Hotspur | Holyhead | The New Oval |
| Holywell Town | Holywell | Halkyn Road |
| Llandudno Junction | Llandudno Junction | Arriva Ground |
| Penrhyncoch | Penrhyn-coch | Cae Baker |
| Porthmadog | Porthmadog | Y Traeth |
| Queens Park | Caia Park, Wrexham | The Dunks |
| Rhyl | Rhyl | Belle Vue |
| Ruthin Town | Ruthin | Memorial Playing Fields |