The change of superconducting transition temperature (T-c) with bond angle in iron-pnictides was investigated by first-principles calculation based on density functional theory. A Green's function method was adopted to estimate the maximum eigenvalue of Eliashberg equation (an indicator of T-c) for NaFeAs with different bond angles. Through calculations the band structure of NaFeAs was obtained. It was found that hole pockets could form at the center of the first Brillion zone in the band structure, which confirmed the existence of superconductivity in NaFeAs. The upper limit of the Fe-As-Fe bond angle for superconductivity was found to be 121 degrees and the highest T-c would occur at the angle of 108 degrees. (C) 2016 Elsevier Ltd. All rights reserved.