  Chiral perturbation theory systematically describes the low energy dynamics
of meson and baryons using nonlinear Nambu-Goldstone fields. Using the Young
tensor technique, we construct the pure mesonic effective operators up to
$p^8$-order, one-to-one corresponding to contact amplitudes with the on-shell
Adler zero condition. The off-shell external sources, non-vanishing under
equation-of-motion conditions, are also added to the operator bases. We also
show the invariant tensor bases using the Young tableau is equivalent to the
trace bases with Cayley-Hamilton relations. Separated into different $CP$
eigenstates, at $\mathcal{O}(p^8)$ we obtain the operator lists of the 567
$C$+$P$+ operators, 483 $C$+$P$- operators, 376 $C$-$P$+ operators, and 408
$C$-$P$- operators for $SU(2)$ case, while there are 1959 $C$+$P$+ operators,
1809 $C$+$P$- operators, 1520 $C$-$P$+ operators, and 1594 $C$-$P$- operators
for $SU(3)$ case, consistent with results using the Hilbert series.
