  In this paper we study Joule-Thomson $(JT)$ expansion of non-linearly charged
$AdS$ black holes in Einstein-power-Yang-Mills (EPYM) gravity in $D$
dimensions. Within the framework of extended phase space thermodynamics we
identify the cosmological constant as thermodynamic pressure and the black hole
mass with the enthalpy and derive the Joule-Thomson coefficient $\mu$.
Furthermore we have presented equations for inversion curves and the exact
expression for the minimum inversion temperature. We also have calculated the
ratio between the minimum of inversion $T_i^{min}$ and the critical temperature
$T_c$ and obtained the analytic expression for the ratio
$\frac{T_i^{min}}{T_c}$ that depends explicitly on the non-linearity parameter
$q$ and dimension $D$. We consider the isenthalpic curves in the $T- P$ plane
for different values of the fixed black hole mass and obtain heating and
cooling region. Finally we have dealt with two limiting masses which
characterizes the process of Joule-Thomson expansion in the $EPYM$ black holes.
