Due to the continuous expansion of the urban scale, the urban metro transportation system also needs to be constantly updated, especially those cities that need to carry mega-events. Larger carrying capacity, better collaboration mode and more optimized operation mode are required to handle the sudden increase in travel demand. The ever-growing micromobility system and the multimodal transport system of micromobility and other public transportation methods can well meet this trend. This thesis aims to develop a multimodal transport optimization model that takes full advantage of the micromobility mode. This thesis, from the perspective of the traffic system administrator, explores the influence of micromobility on the cost of the entire traffic system under the premise of maintaining the normal operation of the metro system after micromobility joins the traffic system at the same level as the metro. Firstly, through literature review, the research object is determined to be a representative shared bike in micromobility mode. The way to deal with the excessive travel demand brought by mega-events is to add shared bikes to the transportation system with the same status as the metro on the basis of maintaining the normal operation of the metro system, and cooperate with the metro system to meet the demand. Secondly, the research methods are qualitative research and quantitative research. In the qualitative research, model design, adjustment and optimization are carried out in combination with actual experience to realize the design of the multimodal transport system of shared bike and urban metro system. In quantitative research, this thesis describes a case study area based on real condition and proposes six scenarios. And through demand forecasting and parameter changes, this thesis explores the situation that only metro participates in the transportation system, and micromobility mode participates in the transportation system with metro with different parameters, etc., under the premise of meeting the excessive travel demand brought by mega-events, impact on total travel costs. Through model optimization and scenario verification, it is concluded that when the micromobility mode participates in the transportation system in a reasonable way, the multimodal transport system will be able to reduce the total cost, and the degree of reduction is related to the characteristics and parameters of the mode.