2017–18 Spartan South Midlands Football League

The 2017–18 Spartan South Midlands Football League season was the 21st in the history of Spartan South Midlands Football League, a football competition in England.

The constitution for Step 5 and Step 6 divisions for 2017–18 was announced on 26 May 2017. Following a few amendments, the constitution for the Spartan South Midlands League was ratified at the league's AGM on 24 June 2017.

Premier Division
The Premier Division featured 20 clubs which competed in the division last season, along with two clubs, promoted from Division One:
 * Biggleswade
 * Harpenden Town

Division One
Division One featured 20 clubs in the division for this season, of which there are five new clubs:
 * Enfield Borough, promoted from Division Two
 * FC Broxbourne Borough, relegated from the Premier Division
 * Maccabi London Lions, promoted from the Herts County League
 * Rayners Lane, transferred from the Hellenic League
 * St Neots Town reserves, promoted from Division Two

Division Two
Division Two featured 14 clubs which competed in the division last season, along with three new clubs:
 * AFC Southgate
 * Berkhamsted Raiders, joined from the Herts County League
 * Park View, joined from the Amateur Football Combination