The invention discloses a microbial sludge deodorizer and a preparation method thereof. The preparation method comprises the following steps: conducting high-density culture on strains of streptococcus thermophilus, bacillus subtilis, aspergillus oryzae, photosynthetic bacteria, saccharomyces cerevisiae, lactobacillus casei and pseudomonas putida; dehydrating and drying the various single strains which are subjected to high-density culture, so that hypopus microbial dry powder is prepared; and mixing the streptococcus thermophilus, the bacillus subtilis, the aspergillus oryzae, the photosynthetic bacteria, the saccharomyces cerevisiae, the lactobacillus casei and the pseudomonas putida according to weight ratio of 10-20 parts of the streptococcus thermophilus, 10-15 parts of the bacillus subtilis, 20-30 parts of the aspergillus oryzae, 10-15 parts of the photosynthetic bacteria, 10-20 parts of the saccharomyces cerevisiae, 10-15 parts of the lactobacillus casei and 10-20 parts of the pseudomonas putida, so that the microbial sludge deodorizer is obtained. The microbial sludge deodorizer provided by the invention is applicable to garbage deodorization; and in comparison with the prior art, the microbial sludge deodorizer is low in production investment, low in production cost and convenient to use, and moreover, the microbial sludge deodorizer is good in deodorizing effect.