The invention provides a system for reusing triple event data of PET. The system includes an input unit, a determining unit, and an output unit. A plurality of data is generated by an object undergoing the PET scan, and the input unit is used to receive the data. The determining unit is used to determine the data and pick out data corresponding to triple event from the data and according to a formula to pick out data corresponding to coincident event from the data corresponding to triple event. In other words, the determining unit picks out data corresponding to true triple event from the data to reuse and analyze the data corresponding to coincident event and further to generate an analysis result. The output unit is used to output the analysis result.
