A prediction method of fatigue strength of polymer composites for an arbitrary frequency, stress ratio, and temperature is proposed. The method is based upon the four hypotheses, (A) failure mechanism for CSR (constant strain-rate), creep, and fatigue failure is the same, (B) the same time-temperature superposition principle holds for all failure strengths, (C) linear cumulative damage law is applicable for specimen failure under nondecreasing stress process, and (D) fatigue strength shows linear dependence upon stress ratio. Satin woven CFRP laminate was chosen as an example of application of the prediction method. The validity of hypotheses B, C, D, and the applicability of this prediction method were experimentally confirmed. It was also confirmed that the hypothesis A is not necessarily always for this prediction method through discussions. Furthermore, the range of combination of fiber and matrix resin to which the prediction method is applicable was shown.