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.