The invention relates to a method for preparing 
ammonium perrhenate from waste liquid containing 
molybdenum and 
rhenium. In the technical scheme of the invention, the method comprises the following steps of: adding 
hydrogen peroxide into the waste liquid containing 
molybdenum and 
rhenium until the solution turns to yellow, then adding a mixed agent until the pH of the solution is 6 to 7, separating by filter pressing, collecting the filtrate, absorbing the filtrate by a resin exchange column, stopping adsorption until the concentration of 
rhenium in 
effluent is constant, eluting with NH3.H2O,collecting the eluate, heating to concentrate the eluate at 98-100 DEG C, cooling, and crystallizing to obtain 
ammonium perrhenate. The mixed agent is a mixture of 
calcium hydroxide and 
calcium oxidein a weight ratio of 5:1. According to the invention, the waste liquid containing 
molybdenum and rhenium, particularly the absorption liquid of the 
flue gas during molybdenum 
roasting, is used as theraw material; the enrichment of rhenium is increased by about 20 times; 
ammonia water is determined as the eluent of rhenium; the 
elution rate of rhenium is higher than 98%; the 
recovery rate of rhenium is higher than 93%, the purity of the 
ammonium perrhenate product is higher than 99.5%, and the economic, social and environmental benefits are significantly improved.