The invention belongs to the technical field of preparation and application of functional nano materials, and particularly relates to a simple preparation method of a sulfydryl-modified gold nanocluster and an application of the sulfydryl-modified gold nanocluster in oxygen quantitative detection, and develops quick oxygen detection test paper for detecting oxygen. The preparation method comprises the following steps: placing chloroauric acid and a polysulfhydryl compounds in deoxygenated water, introducing nitrogen for protection, stirring for 20 to 40 min under a closed room-temperature condition, regulating a pH to 8 by utilizing NaOH, obtaining the sulfydryl-modified gold nano cluster polymer, adding the sulfydryl-modified gold nanocluster polymer into the water, adding sodium hydrosulfite, then adding a hydrochloric acid to adjust the pH to 5, filtering, adding hydrochloric acid to be in strong acidity, precipitating gold nanocluster solids, vacuum drying the solids, and obtaining the sulfydryl-modified gold nanocluster. The prepared sulfydryl-modified gold nano cluster has the characteristics of good solubility, good selectivity and high sensitivity, and can realize the sensitive detection of the content of oxygen and gaseous oxygen in the water.