A smart ultra box adapting to a protective case is disclosed. The protective case can be assembled with a power bank to form a mobile phone protective case. The power bank provides an identification unit. The ultra box includes a main body, a conversion unit, a flexible printed circuit board, a processing unit and a memory unit. The processing unit connects to the conversion unit. The memory unit, connected to the processing unit, stores at least one PIN information. When the protective case assemble with the power bank, the ultra box according to the PIN information determines whether the identification unit is a real identification code of the processing unit; if not, the power bank stops power supply by the processing unit controlled; on the contrary, if yes, the power bank starts power supply by the processing unit controlled.