8. In the Cartesian coordinate system, point $O(0,0)$, $A(0,6)$, $B(-3,2)$, $C(-2,9)$, and $P$ is any point on the line segment $OA$ (including the endpoints). Then the minimum value of $PB + PC$ is $\qquad$ .
8. $5+\sqrt{13}$.

Construct the point $C$'s reflection about the $y$-axis, $C^{\prime}(2,9)$, and let $l_{B C^{\prime}}: y=k x+b$, which intersects the $y$-axis at point $D$.
Solving the system of equations $\left\{\begin{array}{l}2=-3 k+b, \\ 9=2 k+b\end{array}\right.$, we eliminate $k$ and find
$$
b=\frac{31}{5}, D\left(0, \frac{31}{5}\right) \text {. }
$$

Thus, when point $P$ coincides with $A$, $P B+P C$ reaches its minimum, at which time,
$$
P B+P C=5+\sqrt{13} \text {. }
$$