Abstract: In this paper, a method to analyze remaining fatigue life for existing concrete structures is proposed based on reliability theory, in which the number of fatigue-critical cycles under stress ranges is taken as a random variable. The fatigue reliability and remaining fatigue life in different circumstances are studied. It is shown that this method is not only suitable to predicting useful remaining fatigue life with predetermined reliability index but also convenient to calculate corresponding fatigue reliability value with existing or specified frequency of varying loads in a certain service time. The results are instructive for structures in use.