  In this work, we examine the validity of quantum adiabatic theorem in
thermodynamic systems. For a $d$-dimensional quantum many-body system, we show
that the duration time $\tau_0$ required by its ground-state adiabatic process
does not depend on the microscopic details, but the scaling dimension of the
fidelity susceptibility $d_a$. Our result, therefore, provides a quantitative
time scale of the quantum adiabatic theorem in thermodynamic systems. The
quantum adiabatic theorem might be violated in case that the scaling dimension
of the fidelity susceptibility is larger than the system's real dimension
($d_a>d$).
