Nylon 11,11 is a new odd-odd polyamide with multiple crystalline structures. The wide-angle X-ray scattering indicated that the structure of quenched sample was not amorphous but a -form crystal with a relatively low crystallinity. The -form and the -form crystal of nylon 11, 11 could be obtained by annealing the quenched samples at high and low temperature, respectively. No crystal transition happened for the -form sample when annealed at any temperature before melting. However, the -form would quickly transform into the -form when annealed above 145 degrees C. Under the stretching conditions, the -form rapidly transformed into the -form at low temperature, while the -form changed into the -form only at high temperature. These results indicated that the stretching inducement was beneficial to produce the -form, and the thermal inducement was favorable to forming the -form. POLYM. ENG. SCI., 54:2785-2790, 2014. (c) 2013 Society of Plastics Engineers