Abstract Fe nanoparticles and nanochains were prepared by a simple, accessible and pollution-free chemical reduction method. When the concentrations of addition agent NaOH and reagents were changed, the microstructure of Fe nanoparticles and Fe nanochains were distinctive. The magnetic properties of samples were researched, and the influence of the concentration of NaOH and Fe2+ on the microstructure and the magnetic properties of samples has been discussed detailedly. The control of magnetic properties of Fe nanoparticles and nanochains has been realized by adjusting the microstructure via changing the concentration of reagents and addition agent.