The effects of annealing on the physical properties of poly(1-oxotrimethylene) (POTM) fibers were investigated in terms of draw ratio (DR). Annealing increased the degree of orientation with increasing DR. Analysis of wide angle X-ray diffraction patterns and Raman spectra suggested that annealing caused crystal structure transition from the ${eta}$-form to the ${alpha}$-form, which had a denser and more perfect crystal structure. The ${eta}$-form and ${alpha}$-form crystals were favorably formed for as-spun fibers and DR 13 fibers, respectively. In the fiber of DR 4, a combination of both ${alpha}$- and ${eta}$-form crystals was observed. Once the fiber was melted, no melt crystallization took place during cooling. Infrared spectra revealed that the melting process changed the chemical composition of POTM fibers by thermal decomposition, resulting in disappearance of the melt crystallization. In the stress-strain (SS) curve, the as-spun fibers exhibited yield behavior and a plateau region, while the drawn fibers gave a typical SS curve of brittle material without a plateau region. POTM fibers of DR 13 exhibited a significant increase in tensile modulus compared with as-spun and DR 4 fibers.