The invention discloses a fast quantitative detection method for methanogenic archaea in oil-water well output liquid. The fast quantitative detection method comprises the following step: 1, compounding specific primers; 2, preparing standard quality grains; 3, establishing a fluorogenic quantitative PCR reaction process and a reaction system; 4, drawing a standard curve; 3, evaluating the method; 6, sampling a field sample, collecting thalli, and extracting DNA; 7, quantitatively detecting methanogenic archaea of the field sample. The method is high in accuracy, strong in specificity, simple in operation, high in repeatability and short in detection time; the process from extraction of sample DNA to the obtaining of the detection result requires less than 3 h; high performance detection can be performed to 96 samples at the same time; the method is used for fast quantitative detection of methanogenic archaea in oil-water well output liquid.