A heat dissipating system for a data center includes a data center and an air processing unit. The data center includes an enclosure and an electronic device, and defines a first air vent and a second air vent. The air processing unit includes a case and an air processing device. The case defines a first air inlet, a second air inlet, and a first air outlet. At least one air inlet damper is mounted on the case, and a first return air damper is mounted in the case. The data center can adjust cooling based on ambient temperature through the air inlet damper and the first return air damper.