•A quantitative cross-risk assessment method was developed.•The crossover includes the crossover of risk factors and the crossover between jobs.•We explore the degree of crossover between the jobs.•The risk level of crossed risk is divided. The adverse consequences of crossed risk on project construction are far greater than independent risks. Crossed risk includes not only the cross impact of risk factors, but also the mutual influence of crossover job. In the current field of construction safety management and control, there is no relevant research on quantitative methods and grading standards of crossed risk. The purpose of this paper is to develop an assessment method based on the combination of Bayesian network (BN) and the degree of crossover (DoC), which is used to analyze the interrelationship and risk ranking of the crossed risk. According to the sensitivity analysis of the BN model, it is concluded that the most prone to accidents during the construction process are the “three-violation personnel (violating command, illegal operation, and illegal labor discipline)”. DoC as a new conceptual weight is proposed that expresses the overlapped degree of crossover job. According to the developed calculation method, the crossed risk value of the construction project can be obtained. The applicability of the method is demonstrated by a case of a fire and fall accident from a chimney anti-corrosion construction project. This evaluation method can support the quantitative analysis of crossed risk in construction safety, and put forward the strategy of hierarchical control according to the results.