At present, the ore- forming age of sandstone type uranium deposits is mainly determined by U- Th- Pb apparent age of uranium minerals, isochron age of whole rock or uranium minerals samples, and in- situ U- Pb age of uranium minerals. According to the principles, advantages and disadvantages of each method, it is considered that uranium minerals in sandstone type uranium deposits are usually small in size and lack associated minerals to deduct the initial lead.In addition to the isochronal age method, there are great uncertainties in the selection of uranium minerals and the deduction of initial lead isotopes. The advantage of the U- Pb isochron age method is that the whole rock sample analysis data can be used and the influence of the initial lead can be ignored. However, due to the characteristics of the stage mineralization of sandstone type uranium deposits, the scattered distribution of the obtained U- Pb isotopic data in the isochron diagram is often either unable to form a line or the obtained isochron age has no practical geological significance.Combined with the characteristics of episodic mineralization of sandstone type uranium deposits, this paper mainly begins with improving the theoretical basis of isochron age fitting of sandstone type uranium deposits, proposes a method for calculating the last ore enrichment age by using “parallel” isochron method, and further puts forward a comprehensive method to determine the geological significance of ore- forming age by using 238 U- 206 Pb isochron age, 235 U- 207 Pb isochron age, 206 Pb/ 204 Pb-  207 Pb / 204 Pb diagram and initial lead isotopic composition.Based on the data of the whole rock samples of Hadatu, Mengqiguer and Zhajistan uranium deposits, the isochron age calculation results show that the above theoretical method is feasible and can accurately calculate the metallogenic age of sandstone type uranium deposits.The “parallel” isochron method does not need to consider the number of mineralization of uranium ore and the lead isotope content and composition in the last mineralization, and can therefore be applied to the calculation of mineralization age of other types of uranium deposits.