Abstract: Al(OH)3 was introduced as additive to enhance the digestion efficiency of the diaspore ore pulp by sweetening technique and the digestion processs was investigated experimentally, especially effects of the mole fraction of the diaspore pulp before adding the Al(OH)3 in it, digesting temperature, dosage of Al(OH)3 and time for sweetening on the alumina thus produced. The results revealed that the appropriate conditions for digestion process are as follows: the mole fraction of the pulp should be controlled in the range from 1.55 to 1.60; sweetening temperature 210-220°C and time 15-20 min; Al(OH)3 dosage 10%-15% of the pulp. Under such conditions, the digestion efficiency of alumina can be increased to over 88.8% with the mole fraction of the solution less than 1.4 after sweetening process.