An ultracold Fermi gas provides an ideal system to study many-body physics. It could be used as a remarkable test-bed to study many strongly-coupled phenomena, such as high-temperature superconductors, quark-gluon plasma and neutron stars. The ability of precisely controllable interactions and external potential enables us to explore the exotic phase with quantum matter, investigate the quantum non-equilibrium thermodynamics, ultracold collisions and many-body physics in strongly-coupled system. In this paper, we will introduce our recent research on the scale invariant Fermi gases, such as the Efimovian expansion dynamics and the progress of many-body quantum heat engine.