In order to study the crystal structures of Nylon 4 copolymer films by elevating temperature and shooting Xray along the three principal directions (through, edge, and end directions), HT (high temperature) WAXD (wide angle X-ray diffraction) was used. Three conclusions were derived from this work. First, the diffraction intensity of samples was strongest in the edge direction. Also, the diffraction intensity became stronger as the draw ratio increased. Second, the Brill transition appeared at $140^{circ}C$, which indicates that two peaks merged into one peak within the X-ray diffraction intensity graph. Finally, after cooling the specimen for 24 hours, the WAXD data returned to the same initial state.