Fabrication　of　full-densified　Mo　metal　with　fine　grain　size　and　uniform　microstructure　is　highly　desired　to　improve　its　mechanical　property.　In　this　work,　microwave-field-assisted　thermal　sintering　was　utilized　to　promote　the　fast　densification　of　Mo　nanocrystals,　and　the　compact　with　high　relative　density　of　99.8　%　and　fine　grain　size　of　2.09　μm　was　obtained　at　1450°C　for　0.5　h　with　heating　rate　of　20°C/min,　which　is　much　superior　to　the　compact　with　density　of　99.13　%　and　grain　size　of　7　μm　fabricated　by　traditional　thermal　sintering　at　1500°C　for　1　h.　Further　theoretical　and　experimental　investigation　reveals　that　effective　volume　heating　transfer　with　low　activation　energy　provides　strong　driven-force　for　densification　of　nanosized　Mo　powder　at　low　temperature.　　©　Engineered　Science　Publisher　LLC　2021.