Mega sporting events, such as Winter Olympics, have a boosting role for the economic transformation, functional upgrading, and competitiveness improvement of the host cities. The ecological and environmental impacts of mega sporting events are commanding increasing attention. The ecological risk issue is particularly acute with regard to the increasing tournament scale and outdoor venues construction of the Winter Olympics. However, the ecological risks of the Winter Olympic events are difficult to assess quantitatively, being complex and often occurring over extended periods. This paper aims to provide one such approach, relative risk model (RRM), for quantitatively ecological risk assessment connected with human activities and the natural factors. It provides steps of the RRM and a case application of the method in Chongli District, one of host sites of the 24th Winter Olympics in February, 2022. We applied the RRM model to identify the potential stressors from the preparation activities of 2022 Winter Olympic Games. The risks of ecological impacts to assessment endpoints were calculated and ranked by quantitatively determining the interactions of the stressors and habitats as defined in the conceptual model. The critical sets of conclusions were drawn from the assessment. Firstly, the conceptual model of RRM was established including 11 threats, 6 habitats, and 4 ecological assessment endpoints across 6 sub-regions. The ranking criteria were defined by literature review, field investigation, and discussion with local stakeholders. Secondly, the risk assessment was conducted. The most significant stressor was traffic and road/highway construction, while the least threat was fire. The most vulnerable habitat was river course for benthic macroinvertebrates and fish, and the least vulnerable habitats were wetland and ski resort in Chongli. The most significantly affected endpoint was biodiversity, but the least one was recreation function. The highest risk zone was VI region in core area of the 2022 Winter Olympics. Thirdly, the uncertainties associated with both scales of assessment were considerable. The advantages and disadvantages of the RRM were discussed. Despite the uncertainties, the RRM was found to be a robust method for assessing and prioritizing the risks of multiple threats to multiple assets and a useful screening tool for decision-makers in prioritizing management actions. This risk assessment demonstrates the feasibility of using the RRM for assessing risks in a host site of 2022 Winter Olympic Games. The results suggested areas and stressors for restoration efforts in Chongli District, which are valuable for sustainable management of Winter Olympics and local development.