  The kaon identification is crucial for the flavor physics, and also benefits
the flavor and charge reconstruction of the jets. We explore the particle
identification capability for tracks with momenta ranging from 2-20 GeV/c using
the $dE/dx$ measurements in the Time Projection Chamber at the future Circular
Electron-Positron Collider. Based on Monte Carlo simulation, we anticipate that
an average $3.2~\sigma$ ($2.6~\sigma$) $K/\pi$ separation can be achieved based
on $dE/dx$ information for an optimistic (conservative) extrapolation of the
simulated performance to the final system. Time-of-flight (TOF) information
from the Electromagnetic Calorimeter can provide $K/\pi$ separation around 1
GeV/c and reduce the $K/p$ mis-identification rate. By combining the $dE/dx$
and TOF information, we estimate that in the optimistic scenario a kaon
selection in inclusive hadronic $Z$ decays with both the average efficiency and
purity approaching 95\% can be achieved.
