A simplified calculation model of the girder-double noses was constructed by taking the three span concrete continuous girder bridge with equal span as an example in order to reasonably select the parameters such as the length, unit load concentration and bending stiffness of the double launching noses during the launching construction of the multi-span concrete continuous girder bridge. The balance equation of each node was established by displacement method, and the analytical expression of internal forces of each node was derived. The influences of different launching nose parameters on the maximum negative moment at fulcrum and the maximum positive moment within the span were analyzed, and the variation rule of the internal forces of the girder during the launching construction was revealed. Then a reasonable and rigorous method for optimizing the launching nose parameters was proposed by taking the numerical example of a real bridge as an example, and the optimal launching nose parameters were obtained. The internal force variation rule of unequal span continuous girder bridge was analyzed according to the different length of front and rear launching nose. Results show that the launching stage is affected by the length of launching nose in the continuous girder bridge with equal span, and it is more complicated for the continuous girder bridge of unequal span. In the unequal span continuous girder bridge, the length of rear launching nose has little effect on the maximum negative moment at fulcrum, while the length of front launching nose has great effect on the maximum negative moment at fulcrum. In the real bridge example, the optimal length ratio, unit load concentration ratio and bending stiffness ratio of the launching nose are 0.78, 0.14 and 0.39 respectively. The proposed optimization method for launching nose parameters is simple and can be used for optimization of different section forms.