The invention provides a synchronous rapid detection method of a physicochemical index near infrared spectrum of biogas liquid and belongs to the technology of detection of anaerobic fermentation solutions. The method comprises the following steps: collecting a sample, carrying out physicochemical index determination, acquiring a near infrared spectrum, pre-treating the spectrum and dividing a sample set and optimizing a characteristic wavelength based on a dual genetic-simulated annealing algorithm; then establishing a corresponding partial least square regression model through spectrum dataof a correction set according to biogas liquid chemical oxygen demand optimized through the dual genetic-simulated annealing algorithm, volatile fatty acid and the characteristic wavelength of an ammonia nitrogen physicochemical index; evaluating the precision of the regression model by utilizing an identification set; establishing a rapid detection model; after centrifuging a biogas liquid sampleneeding to be subjected to physicochemical index detection, taking supernatant and carrying out near infrared spectrum scanning; then inputting into the detection model according to the optimized physicochemical index characteristic wavelength, so as to finish synchronous rapid detection of the physicochemical index of the biogas liquid. The method is large in detection speed, high in precision and comprehensive in detection items.