Shaun MacDonald had the Cherries ahead in the 23rd minute with a flying header which appeared to have the Dorset club safely through to the next stage of the league cup before Jordan Hugill bobbed up for the Lilywhites.
His 84th-minute header from Gregory Cunningham's lovely back-post ball sent the match into added time with Bournemouth drawing first blood through Marc Pugh's close range finish in the 96th minute.
Preston were able to fight back once again, this time with two minutes remaining when Daniel Johnson converted from the spot after Pugh had been penalised for handball.
Johnson's expert spot-kick sent the match into a shootout which saw the Cherries escape with a 3-2 win thanks to the heroics of Adam Federici who denied Hugill, Alan Browne and Johnson from 12 yards to send his side through.
2015/16 CAPITAL ONE CUP - THIRD ROUND