The invention discloses a frequency method-based suspender tension determining method. The method comprises the following steps of: measuring the transverse vibration frequency omega of a suspender; and acquiring suspender tension according to an analytical expression between the suspender tension T and the transverse vibration frequency omega under the condition of complex boundaries, wherein inthe analytical expression, K'g=Kg+K1, K'X=KX+K2, Mg is equivalent mass of an arch rib, Mx is equivalent mass of a tie beam, the Kg is axial equivalent rigidity of the arc rib to the suspender, the Kxis axial equivalent rigidity of the tie beam to the suspender, the K1 is axial equivalent rigidity of an anti-vibration pad in the arc rib to the suspender, the K2 is axial equivalent rigidity of an anti-vibration pad in the tie beam to the suspender, K3 is rotary equivalent rigidity of the arc rib to the suspender, K4 is rotary equivalent rigidity of the tie beam to the suspender, m is mass of the suspender in unit length, EI is flexural rigidity of the suspender, and L is calculated length of the suspender. By the method, boundary constraints such as additional mass, elastic supporting and the like of the suspender are relatively fully considered, and calculation results are relatively accurate for both short suspenders and long suspenders in spite of complicated forms.