In order to evaluate the effects of working loads on the connecting stiffness of double-row curvic couplings, a parametric three-dimensional model of the double-row curvic couplings is established and the static lateral stiffness and torsional stiffness are calculated using the finite element method with various working loads taken into account. In the simulations, the thermal load, the bolt load and the maneuvering load is considered respectively. The results show that, with a bolt pre-tightening force of 4 × 104 N, the lateral stiffness is 3. 89 × 109 N/m when the thermal and maneuvering loads are neglected. As the working temperature increases from 20 ℃ to 650 ℃, the lateral stiffness is decreased by about 30%. If the bolt pre-load is high enough, and the curvic couplings is in rigidity saturation state, the lateral stiffness is only slightly affected by the bolt pre-load. The results of this study provide some reference for calculating the rotor dynamics characteristics of rotors with curvic couplings under working conditions.