The invention relates to a differential pressure piezoelectric generating device, comprising a disturbing body and a piezoelectric piece, wherein a side surface of the disturbing body is an arc-shapedside surface whose radian is gradually increased from one end to the other end; the piezoelectric piece is arranged on the arc-shaped side surface of the disturbing body; a space is arranged betweenthe piezoelectric piece and the disturbing body; and the piezoelectric piece is opposite to the arc-shaped side of the disturbing body. The piezoelectric generating device provided by the invention issimple in structure, and is simple in power generation principle, and drives the piezoelectric piece to generate bending vibration by using a variable pressure difference of seawater on both sides ofthe piezoelectric piece, so that the piezoelectric piece generates charges in the thickness direction so as to realize piezoelectric power generation.