  The implications of the $f_1(1285)-f_1(1420)$ mixing for the
$K_1(^3P_1)-K_1(^1P_1)$ mixing angle is investigated. Based on the
$f_1(1285)-f_1(1420)$ mixing angle $\sim 50^\circ$ suggested from the analysis
for a substantial body of data concerning the $f_1(1420)$ and $f_1(1285)$, the
masses of the $K_1(^3P_1)$ and $K_1(^1P_1)$ are determined to be $\sim
1307.35\pm 0.63$ MeV and $1370.03\pm 9.69$ MeV, respectively, which therefore
suggests that the $K_1(^3P_1)-K_1(^1P_1)$ mixing angle is about $\pm (59.55\pm
2.81)^\circ$. Also, it is found that the mass of the $h^\prime_1(^1P_1)$
(mostly of $s\bar{s}$) state is about $1495.18\pm 8.82$ MeV. Comparison of the
predicted results and the available experimental information of the $h_1(1380)$
shows that without further confirmation on the $h_1(1380)$, the assignment of
the $h_1(1380)$ as the $s\bar{s}$ member of the $^1P_1$ meson nonet may be
premature.
