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We revisit the diagonal ridge feature (diagonal distributions in the $R,v_{\phi}$ plane) found in $Gaia$ and present timing analysis for it betweenGalactocentric distances of $R=7.5$ and 12 \,kpc, using Main-Sequence-Turn-Offand OB stars selected from the LAMOST Galactic spectroscopic surveys. Werecover the ridge pattern in the $R$--$v_{\phi}$ plane color coded by meanradial velocity and find this feature is presented from very young (OB stars,few hundred \,Myr) to very old populations ($\tau$ = 9$-$14 \,Gyr). Meanwhile,some ridge features are also revealed in the metallicity [Fe/H], [$\alpha$/Fe]and $v_{z}$ distributions. In the $L_{Z}, v_{\phi}$ plane, one of the ridgepatterns, with constant angular momentum per unit mass, shows variations withdifferent age populations compared. However, the remaining two ones arerelatively stable, implying there might have two kinds of ridge patterns withdifferent dynamical origins and evolution.

Diagonal Ridge pattern of different age populations found in Gaia DR2 with LAMOST Main-Sequence-Turn-Off and OB type Stars