LNT control method for vehicle

An LNT (Lean NOx Trap) control method for vehicles increases a purification rate of NOx while preventing an increase in the amount of slip of separated NOx at a relatively low LNT temperature. The method includes a recycle necessity determining step that determines whether to recycle NOx of a LNT in accordance with an amount of adsorbed NOx, a LNT temperature determining step that determines whether a temperature of the LNT is below a predetermined reference temperature, a rich performing step that performs a rich mode when the temperature of the LNT is equal to the reference temperature or above and a pre-rich step that ejects fuel in a rich state when the temperature of the LNT is below the reference temperature.