We consider weak solutions to a two-dimensional simplified Ericksen-Leslie system of compressible flow of nematic liquid crystals. An initial-boundary value problem is first studied in a bounded domain. By developing new techniques and estimates to overcome the difficulties induced by the supercritical nonlinearity |∇d| 2 d in the equations of angular momentum on the direction field, and adapting the standard three-level approximation scheme and the weak convergence arguments for the compressible Navier-Stokes equations, we establish the global existence of weak solutions under a restriction imposed on the initial energy including the case of small initial energy. Then the Cauchy problem with large initial data is investigated, and we prove the global existence of large weak solutions by using the domain expansion technique and the rigidity theorem, provided that the second component of initial data of the direction field satisfies some geometric angle condition.Keywords: Liquid crystals, compressible flows, weak solutions, Galerkin method, weak convergence arguments. 2000 MSC: 35Q35, 76D03.where ρ is the density of the nematic liquid crystals, v the velocity and P (ρ) the pressure, d ∈ S 1 := {d ∈ R 2 | |d| = 1} represents the macroscopic average of the nematic liquid crystal orientation field. The constants µ, λ, ν, and θ denote the shear viscosity, the bulk viscosity, the competition between kinetic energy and potential energy, and the microscopic elastic relation