The 2004–05 Spartan South Midlands Football League season is the 8th in the history of Spartan South Midlands Football League a football competition in England.
| Competition: | Spartan South Midlands Football League Premier Division |
| Season: | 2004–05 |
| Winners: | Potters Bar Town |
| Promoted: | Potters Bar Town |
| Relegated: | Bedford United & Valerio Hoddesdon Town |
| Matches: | 380 |
| Total Goals: | 1194 |
| Prevseason: | 2003–04 |
| Nextseason: | 2005–06 |
The Premier Division featured 16 clubs which competed in the division last season, along with four clubs, promoted from Division One:
| Competition: | Spartan South Midlands Football League Division One |
| Season: | 2004–05 |
| Winners: | Oxhey Jets |
| Promoted: | Biggleswade United Oxhey Jets |
| Matches: | 272 |
| Total Goals: | 1057 |
| Prevseason: | 2003–04 |
| Nextseason: | 2005–06 |
Division One featured eleven clubs which competed in the division last season, along with six new clubs.
| Competition: | Spartan South Midlands Football League Division Two |
| Season: | 2004–05 |
| Winners: | Crawley Green |
| Promoted: | Dunstable Town 98 |
| Matches: | 240 |
| Total Goals: | 927 |
| Prevseason: | 2003–04 |
| Nextseason: | 2005–06 |
Division Two featured twelve clubs which competed in the division last season, along with four new clubs:
Also, Old Dunstablians changed name to AFC Dunstable and Abbey National changed name to Loughton Orient.