A buffer and return device for a slide rail in a drawer attached to an outer rail of the drawer and includes a base, a buffer plunger and an elastic element. The base has a base chamber at a front section thereof. The base chamber has an air passage, a lateral passageway at another section thereof and a bend bottom slot. The buffer plunger has a size corresponding to the base chamber. The elastic element has an end thereof fixed to a front end of the base chamber. The retaining plate has a holding way for a lock piece of an inner rail in the slide rail moveable between a locked and released positions and is connected with the buffer plunger and the elastic element with a lower projection at a bottom thereof for passing through the bottom slot. Once the drawer is pulled outward and then pushed inward, the buffer plunger squeezes the air in the base chamber to forceably discharge via the air passage so as to slowly return the drawer to an initial position.