The present study investigates the deformation behavior of Poly-Ether-Ether-Ketone (PEEK) at elevated temperatures and low strain rates through a combination of experiments and simulations. Uniaxial tension tests at elevated temperatures (293–543 K) and strain rates (8.3 × 10−3 to 3.3 × 10−1 s−1) were performed, and the temperature- and rate-dependencies of the deformation behavior and mechanism of PEEK were discussed in detail. The Erichsen test was performed at temperatures varying from 473 to 533 K and a fixed speed of 1 mm/s. Based on an investigation of numerous constitutive models, a phenomenological model called DSGZ was employed in ABAQUS/Explicit to characterize the deformation behavior of PEEK at elevated temperatures, and the deviation between experimental and simulation data was less than 10% at large deformations. Moreover, the simulation results accurately predicted the necking and cold drawing phenomena in the tension test as well as the deformation in the Erichsen test.