Swindon took the lead on 15 minutes with a close range header goal from Scott Cuthbert giving Swindon a 1-0 lead.
On 27 minutes Swindon were reduced to ten men after Jonathan Douglas was shown a straight red card for a tackle which the referee classed as two footed.
On 64 minutes Millwall were also reduced to ten men for a high challenge on Jon-Paul McGovern which saw Andy Frampton shown a straight red. Neil Harris for Millwall, and Kevin Amankwaah were both booked as well.
On 82 minutes Millwall equalised with a goal from Danny Schofield.
Millwall came close to getting a winner, but Swindon held on for another 1-1 draw. This leaves Swindon in 7th place ahead of next Saturday's home game to Hartlepool.