W-30Cu composite powder fabricated by sol-spray drying and subsequent hydrogen reduction was pressed and directly liquid phase sintered at 1340~1420 ℃ for 15~120 min, the densification and grain growth mechanism were studied. The results show that the significant densification occurs in the early sintering stage of the liquid phase. When sintered at 1340 ℃ for 15 min, the relative density reaches above 90%. With the sintering time increases, the relative density increases. When sintered at 1380 ℃ for 90 min, the maximum relative density of 99.1% is obtained. During liquid sintering, W grains grow up as spherical shape, and the grain size G and sintering time t matches the relationship G3∝ kt, which means that the grain growth of W is subjected to the dissolution-precipitation mechanism. When sintered in the range of 1340~1420 ℃, the grain growth kinetic coefficients increase from 1.61×10?2 to 4.65×10?2μm3/min. The results suggest the formation of liquid, particle rearrangement, dissolution-precipitation and grain growth cause nano-sized W-30Cu composites to reach nearly full density