The invention relates to a method for extracting tungsten trioxide and molybdenum trioxide by pretreating tungsten-molybdenum concentrates with a concentrated acid, which comprises eight flows of pretreatment with the concentrated acid, lixiviation, molybdenum precipitation, the preparation of MoO3 by roasting, ammonia leaching, concentration, cooling for crystallization, and the preparation of WO3 by roasting. The flows have the advantages that: 1, the recovery rate is high, the process is simple, the flows are short, the total recovery rate of molybdenum is between 95 and 98.5 percent, and the total recovery rate of the WO3 is between 96 and 97.5 percent; and 2, the separation of tungsten and the molybdenum is realized, in the process flows, the solubility of the molybdenum and the tungsten in the acid is different, and thus, according to the principle, the tungsten content of the molybdenum trioxide is less than or equal to 0.4 percent, the molybdenum content of leaching residues (tungsten concentrates) is less than or equal to 0.3 percent, so that the separation of the tungsten and the molybdenum is realized. Tungsten-molybdenum concentrate resources are utilized fully, so themethod has excellent social and economic benefits.