In order to explore the effect of cognitive load on workers' hazard identification behavior，a cognitive experiment based on eye-tracking technology for construction site hazard identification was designed firstly. In this experiment，a N-digit task was introduced to increase the cognitive load. Secondly，the gaze and glance data were collected to analyze the static attention allocation，and the scanning path was processed to extract the dynamic transfer characteristics of attention. Finally，three parameters of variance review probability (RP)，transition probability (TP) and switching probability (SP) were selected as the quantitative parameter values to classify the scanning patterns of hazard identification，which explored the influence of cognitive load on hidden hazard identification from the perspective of visual behavior performance. The results show that the level of cognitive load negatively affects hazard identification performance. The subjects with high cognitive load show longer first fixation time，fewer fixation counts and saccade counts，and there is no significant difference in fixation percentage and mean fixation duration. Additionally，based on the attention characteristics，three scanning patterns are identified: sequential inspection，repeated comparison and random discovery. With the improvement of cognitive load level，subjects will pay more attention to identifying single hazard but neglect others during sequential inspection，and reduce the attention in the hazard area but still keep the fixation point quickly and frequently switching during repeated comparison，while the number and time of inspection of hazard areas are reducing simultaneously during random discovery.