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In this paper, hollow ammonium paramolybdate precursor microspheres were prepared from ammonium paramolybdate solution by spray drying, and they were calcined and reduced to square or spherical molybdenum. It was characterized that the morphology of the ammonium paramolybdate precursor microspheres, and the morphology and composition were studied after calcination and reduction of ammonium paramolybdate precursor microspheres. The effects of reduction temperature, heating process and atmosphere on the reduction of ammonium paramolybdate precursor microspheres were also investigated. Consequently, as the concentratione of solution increase, the particle size range of microspheres become bigger, pits in the surface increase, and the agglomeration phenomenon becomes more obvious; with the increase of feed rate, the particle size range of microspheres decreased a little, and pits in the surface decrease; with the increase of spray drying temperature, the particle size range first increase and then decrease, while pits in the surface increase evidently; at the temperature of 800℃，the square or near spherical molybdenum can be obtained by hydrogen-argon mixer reduction, while the spherical molybdenum can be obtained by pure hydrogen reduction.