The present invention discloses a process for producing nano-powders and powders of nano-particle loose aggregate, which includes: (a) providing at least two reactant solutions A and B capable of rapidly reacting to form deposits; (b) supplying the at least two reactant solutions A and B at least at the reaction temperature into a mixing and reaction precipitator respectively, in which mixing reaction and precipitation are continuously carried out in sequence, the mixing and reaction precipitator being selected from at least one of a tubular ejection mixing reactor, a tubular static mixing reactor and an atomization mixing reactor; and (c) treating the deposit-containing slurry continuously discharged from the mixing reaction precipitator.