We present stellar density maps of the Galactic outer disc with red clump stars from the LAMOST data .
These samples are separated into younger ( mean age \sim 2.7 Gyr ) and older ( mean age \sim 4.6 Gyr ) populations so that they can trace the variation of the structures with ages in the range of the Galactocentric radius R from 9 to 13.5 kpc .
We show that both the scale heights for the two populations increase with R and display radial gradients of 48 \pm 6 and 40 \pm 4 pc/kpc for the older and younger populations , respectively .
This is evident that the flaring occurs in the thin disc populations with a wide range of ages .
Moreover , the intensity of flaring seems not significantly related to the age of the thin disc populations .
On the other hand , the scale lengths of the radial surface density profiles are 4.7 \pm 0.5 kpc for the younger and 3.4 \pm 0.2 kpc for the older population , meaning that the younger disc population is more radially extended than the older one .
Although the fraction of the younger population mildly increases from 28 % at R \sim 9 to about 35 % at R \sim 13 kpc , the older population is prominent with the fraction no less than 65 % in the outer disc .