The invention belongs to the technical field of chemical catalysts, and specifically provides a ruthenium supported hydroxyapatite (HAP) catalyst, a preparation method thereof and application of the ruthenium supported hydroxyapatite catalyst in N2O decomposition. The catalyst is ruthenium supported hydroxyapatite. The coprecipitation method is performed to synthesize HAP, and the HAP is soaked in rhodium nitrate and then roasted to obtain the ruthenium supported hydroxyapatite calayst (Rh/HAP). The catalyst of suck type can be applied to direct catalytic decomposition reaction of N2O, is relatively high in activity and stability, and has the catalytic activity obviously superior to that of the general carrier ruthenium supported catalysts.