A semi-automatic foot-pedal device is provided, which comprises a panel and a pedal-connecting component connected with the panel. The pedal-connecting component comprises an upper bracket, a left bracket, a lower bracket, a right bracket and an elastic unit; when the pedal-connecting component is in a closed state, the panel moves away from the upper bracket to transform the pedal-connecting component into an elastically spread state under a force on the panel in a downward direction; when the pedal-connecting component is in a spread state, the panel moves towards the upper bracket to transform the pedal-connecting component into an elastically closed state under a force on the panel in an obliquely-upward direction. The semi-automatic foot-pedal device of the present disclosure has a novel structure, and does not need a conventional motor system, so it saves the electric power and is safer to use.