The invention relates to a preparation method for a gold-loaded tin oxide nanometer material for detecting hydrogen. In order to deal with the conditions that hydrogen detecting gas sensitive materials are low in sensitivity, low in response speed and poor in stability, the gold-loaded tin oxide nanometer material is made from potassium stannate, chloroauric acid and glucose and prepared through the steps of hydro-thermal synthesis through a reaction still, vacuum heat treatment and grinding and sieving. According to the preparation method, the process is advanced, and data are full and accurate; products are atropurpureus crystals, the crystal particle diameter is smaller than or equal to 80 nm, and the product purity is high and reaches 99.6%; the gas sensitivity of the material on 100 ppm hydrogen reaches 25, response time is 1 s, and recovery time is 3 s; the sensitivity is high, response and recovery are fast, and the material can be applied to a gas sensor for detecting hydrogen. The preparation method for the gold-loaded tin oxide nanometer material is quite advanced.