Some inevitable disadvantages (being thick and heavy with narrow broadband) restrict the application of Cu-based absorbers in microwave absorption field, which can be overcome by finely modulating the morphology and component of 1D structures. Here, we reported ethylenediamine-steered in situ two-step reduction reactions, which allowed the tunable preparation of CuxNi1-x(x = 0, 0.005, 0.02, 0.0344, 0.0934, 0.1581, 0.2243, and 1) composites with continuously tunable components and morphology varying from smooth rods to urchin-like rods and microspheres. The recombination of Ni with Cu into Cu(x)Ni(1-x)composites can tune crystallite size, inner stress, lattice constant, component, shape as well as properties. The CuxNi1-x(x = 0.0344-0.1581) composites exhibited stronger and wider absorption band under a lower filling mass fraction and thinner sample than other Cu-based absorbers. Due to the combined action of double dielectric relaxation, double magnetic resonances, high attenuation, and good impedance match. The optimal microwave absorption capability (MACs) was achieved for Cu(0.0344)Ni(0.9656)microspheres with a maximum RL value of - 67.5 dB at 14.74 GHz and a broad frequency band (99% attenuation) of 15.41 GHz, corresponding to 1.7-10 mm sample thickness. Owing to tunable saturation magnetization and excellent MACs, the Cu(x)Ni(1-x)composites can work as a kind of promising absorber for applications in electronic equipment and devices.