Abstract: The construction process of an engineering project is vulnerable to the impact of resource conflicts，which will lead to deviations in the project plan. In order to reduce the impact of resource factors on the project schedule, a critical chain buffer zone setting method based on resource flexibility is proposed. Firstly, according to the Resource-Ability-Matrix (RAM)，the tension of human resource flexibility and resource are defined and measured. Then, according to the human resource flexibility and resource tension, resource buffer and feeding buffer are calculated and allocated. The critical chain buffer setting model based on resource flexibility is obtained. Finally, an example is introduced to verify the validity of the method. The results show that the buffer setting model considering human resource flexibility and resource tension can effectively reduce the impact of resource risk on the project schedule, improve the completion probability and shorten the project planning period.