The invention discloses an online traffic bearing capacity evaluation system. The invention relates to the technical field of traffic planning, urban planning and urban management. The system mainly comprises a cloud computing server composed of a cloud computing traffic model and a spatial database. The user side is composed of an evaluation parameter input module, a matched road planning module,a land planning module, a plot entrance and exit setting module and a traffic influence prediction display module; the spatial database stores basic electronic maps, electronic maps, background OD data, road network data, road condition data, mobile phone signaling data and enterprise internet LBS data of a plurality of regions. According to the method, big data, cloud computing and a traffic model can be organically combined, a user can complete all work from planning scheme input to online traffic bearing capacity evaluation only by following sequential operation of a client system, obviously, online traffic bearing capacity evaluation can be realized with high efficiency and high precision, and actual application requirements are met.