Pressureless sintering of pure -Y2Si2O7 powders that had been synthesized by a solid-liquid reaction method using Y2O3 and SiO2 powders with Li2O, MgO, and Al2O3 additives was reported. The sintering kinetics of -Y2Si2O7 powders was analyzed to track details of densification evolution. Apparent activation energies of the densification of -Y2Si2O7 powders were reported for the first time, which was 57.1, 96.6, and 100.2kJ/mol for the powders with Li2O, MgO, and Al2O3 additives, respectively, indicating that Li2O could promote the densification behavior effectively. The flexural strengths as a function of temperature for the -Y2Si2O7 ceramics with different additives were also investigated. The degradation of high-temperature flexural strength was mainly ascribed to the softening of grain-boundary glassy phase. -Y2Si2O7 specimens fabricated using the powders with MgO or Al2O3 additives exhibited better high-temperature mechanical properties.