Nanocrystalline Mo-18Cu, Mo-30Cu and Mo-40Cu (wt%) composite powders were fabricated by sol-spray drying, calcinating and subsequent hydrogen reduction process. The sintering behavior of nanocrystalline Mo-Cu composite powder and the influence of the copper content on the sintering densification process were investigated. The result shows that nanocrystalline Mo-Cu composite can obtain a fully dense structure. Particularly, Mo-30Cu and Mo-40Cu sintered at 1050-1200 °C can achieve relative densities over 98% and attain fine-grain structures. The relative density of Mo-18Cu sintered at 1350-1400 °C can also reach 98%, while a coarse structure with a mean grain size of 5 μm is obtained due to the remarkable grain growth in the compact. According to the compositional analysis, metastable Mo (Cu) solid solution forms in the composite powder. However, with the increase of the sintering temperature, Cu precipitates gradually from the metastable Mo (Cu) solid solution.