The Latics were two goals up at the break and the visitors could not have complained had it been a bigger margin.
Deane Smalley’s cross was met on the edge of the box by Chris Taylor who hit home.
Matt Wolfenden put a backheel just wide on the half-hour mark and Neil Eardley had a 20-yard shot tipped around the post in the 42nd minute.
Seconds later Oldham grabbed a well worked second goal as Mark Allott let fly with an explosive shot which keeper Glenn Morris never saw.
But he rescued Orient in the 58th minute by denying the busy Smalley. Teenage substitutes Aaron Chalmers and Ashley Kelly made their debut for the hosts who used five other players aged 21 or under.