Abstract: In order to develop a method for predicting the fluidelastic instability of the tube bundle without relying on experiments, a hybrid fluidelastic instability prediction method for tube bundle is proposed by using CFD to capture drag and lift coefficients and their spatial derivatives, and substituting them into the quasi-static theory for fluidelastic instability. The developed method accounts for the instability of a tube bundle for both cross-flow and in-flow directions. Taking the normal triangle tube bundle as a typical example, the fluidelastic instability of two pitch ratios was performed. The results show that the prediction method of the elastic tube bundle fluidelastic instability based on the CFD and quasi-static theory hybrid can obtain the critical velocity of fluidelastic instability of the tube bundle without experimentation. The fluidelastic instability results calculated by this method are in good agreement with experimental results in literature.