Sintered intermetallic Ag3Sn powders by spark plasma sintering (SPS) have been studied in order to analyse the effect of the microstructure on the transport properties at room temperature. Firstly, we synthesized Ag3Sn submicronic particles by polyol process. Then, we sintered them by SPS at different temperature (473K, 573K and 663K) and pressure (20 MPa and 100 MPa) using fixed dwelling time of 5 min. X-Ray Diffraction (XRD) and Differential Scanning Calorimetry (DSC) show that all sintered samples remained single-phased according to the Ag3Sn orthorhombic crystal structure. Their corresponding grain size (≈ 0.65 to 1.75 µm) and relative density (≈ 88% to 98%) were calculated and show similar evolution respect to the sintering parameters. As a matter of fact, sintering temperature remains the key factor to affect the microstructure of the sintered materials. Finally, the thermal conductivity and the electrical resistivity were investigated at room temperature by using the Flash Laser technique and the Physical Property Measurement System (PPMS) respectively. Values of these latter were highly dependent to densities and grain sizes showing the key role of the microstructure and thereby confirming the fact that Ag3Sn compound is a good candidate for a lead-free die-attach material in power module devices.