The intermetallic complexes of rare-earth and 3d transition metals with core-shell structures are commonly employed as microwave absorbing materials due to their high saturation magnetizations and natural resonance in GHz. Hence, we synthesized Y$_2$Co$_{17}$ alloy via the co-precipitation reduction-diffusion technique, then coated the Y$_2$Co$_{17}$ magnetic powders with SiO$_2$ to create Y$_2$Co$_{17}$@SiO$_2$ core-shell structures.The formation of Y$_2$Co$_{17}$@SiO$_2$/polyurethane (PU) at various volume fractions and their magnetic, electromagnetic properties were investigated using XRD, SEM, EDS, and VNA. The microwave absorption characteristics of Y$_2$Co$_{17}$@SiO$_2$/PU were also investigated at various volume fractions. We not only investigate the zero-reflection conditions of the samples with different volume fractions, but also show that every absorber has a strong reflection loss value (RL$ \le -65.00$ dB) and excellent microwave absorption properties with an average reflection loss (RL) of Y$_2$Co$ _{17}$@SiO$_2$/PU being below $-10$ dB at $8-18$ GHz under different thicknesses, showing the enhancement of microwave absorption performance arises from the balance between permeability and permittivity of absorber.