The Blues were in firm control of the match with 66 minutes played courtesy of goals from Juan Mata and Frank Lampard.
Mata stuck on the stroke of half-time to open the scoring with Lampard's well-placed header seemingly wrapping up the points.
However, the introduction of Adam Le Fondre changed the game. He pulled one back with three minutes to go before snatching a point with virtually the last kick of the game.
Chelsea were in control in the first half, however, they were unable to convert their domination of possession and territory into clear-cut chances.
They made the breakthrough just before half-time when Fernando Torres dinked a lovely through-ball in for Mata who lashed home a left-footed shot - the first attempt on target in the half.
The Blues carried their dominance into the second half and the game looked dead and buried in the 66th minute when Mata's corner was met by Lampard who finished with aplomb into the top corner.
Reading manager Brian McDermott made changes late on as the Royals attempted to get back into the game, but it seemed more likely Chelsea would add a third rather than concede.
Blues substitute Yossi Benayoun found Brazilian Oscar, but Adam Federici came out quickly to close down the midfielder and make the block.
Out of the blue the Royals pulled one back. Two substitutes combined as Hope Akpan played in super-sub Le Fondre who lashed home a first-time effort past Ross Turnbull.
And their comeback was completed with virtually the last kick of the game as Reading lumped the ball forward from a free-kick. Jimmy Kebe nodded the ball on for Akpan who kept things alive and it fell nicely for Le Fondre to guide the ball home and level the match.