The invention belongs to the field of stock feed and relates to a preparation method of cassava residue complete biochemical feed for sheep. According to the preparation method, fresh cassava residues, sheep fine feed, grass meal, molasses, calcium hydrophosphate, microbial stains and table salt are uniformly mixed to obtain mixing materials, the moisture content in the mixing materials is controlled to be 40 percent to 50 percent, then, the anaerobic airtight fermentation is carried out for more than five days, and the cassava residue complete biochemical feed for sheep is obtained. The preparation method has the advantages that according to the sheep growth and development requirements, raw materials including the fresh cassava residues are used as major feed raw materials, the sheep fine feed, the grass meal and the like are scientifically prepared, the process is simple, the cost is low, the obtained feed can inhabit the propagation of digestive tract pathogens, the sheep immunity is improved, the palatability and the digestive absorption of the cassava residues are improved, the problem of feed shortage of captive breeding sheep is solved, and the complete biochemical feed belongs to the sheep complete high-quality feed with a health care function.