An activation system is applied to a computer apparatus. An activation signal is received by the computer apparatus to implement a booting action. The system comprises an external power adapter and a detection unit. An external power is received by the external power adapter. The external power then is provided to the computer apparatus. Meanwhile, a power supply signal then is generated by the external power adapter. The power supply signal is detected by the detection unit. The activation signal is outputted by the detection unit after detecting the power supply signal, so as to boot the computer apparatus through the external power.