The properties and electronic structure of Fe under pressures of 0-30GPa have been studied by first principles employing the density functional theory (DFT), the ultra-soft pseudo-potentials (USPP) and the generalized gradient approximation (GGA). The calculating results show that there is a structural transition from magnetic body-centered cubic (bcc) to nonmagnetic hexagonal-close-packed (hcp) structure for Fe around 11GPa pressure. There is a pseudogap both in the density of states (DOS) for bcc and hcp Fe. The pseudogap of bcc Fe is deeper and wider than that of hcp Fe. The elastic modulus is obtained by Voigt-Reuss-Hill averaging scheme. The results indicate that the elastic properties of bcc Fe enhance with pressure except for elastic stiffness constant C11, shear modulus G and elastic modulus E at the transition pressure, while the elastic properties of hcp Fe increase linearly with pressure. Magnetic bcc Fe is ductile, and hcp Fe becomes ductile from brittle around 25GPa. © Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg 2011.