  In this paper, we consider the inviscid limit of inhomogeneous incompressible
Navier-Stokes equations under the weak Kolmogorov hypothesis in $\mathbb{R}^3$.
In particular, we first deduce the Kolmogorov-type hypothesis in
$\mathbb{R}^3$, which yields the uniform bounds of $\alpha^{th}$-order
fractional derivatives of $\sqrt{\rho^\mu}{\bf u}^\mu $ in $L^2_x$ for some
$\alpha>0$, independent of the viscosity. The uniform bounds can provide strong
convergence of $\sqrt{\rho^{\mu}}\bf u^{\mu}$ in $L^2$ space. This shows that
the inviscid limit is a weak solution to the corresponding Euler equations.
