A temperature control system includes a temperature sensing module, a temperature control module, a pulse width modulation control module, a heating module, a heat dissipating module, and a switch module. The temperature sensing module is configured to obtain a current ambient temperature in a test box. The temperature control module is configured to output a control signal according to a difference between the current ambient temperature and a reference temperature. The pulse width modulation control module is configured to output a pulse width modulation signal according to the control signal. The switch module is configured to instruct the heating module or the heat dissipating module according to the pulse width modulation signal to keep the current ambient temperature generally equal to the reference temperature in the test box.