The fluorescence lifetime detection technology which was the key technique for optical fiber fluorescence temperature sensor was studied. The method of Pulse modulated PLD with two references (PLD-PMTR) was adopted in this paper. And the lifetime of fluorescence fiber temperature sensor was detected. The mathematic model has been deduced. This method has a high signal to noise ratio and can restrain the excitation leakage. The measurement output of system can be transferred faithfully over long distance and it easy to interface with a computer. Through experiments the method is efficient and practical. It can attain the demand of the system.