An electronic device module includes an electronic device, a rack accommodating the electronic device, and a shield adjusting assembly. The rack defines a number of ventilation holes, and the shield adjusting assembly defines a number of through holes. The electronic device is placed in the rack to drive the shield adjusting assembly to a first position in which the through holes align with the ventilation holes. When the electronic device is detached from the rack, the shield adjusting assembly is restored by a resilient element to a second position in which the through holes offset the ventilation holes such that the ventilation holes are shielded.