Pulsed electric fields can induce various kinds of biological effects that are essentially different from the normal electric fields, especially the interactions of Nanosecond Pulsed electric field (nsPEF) with cells. The biological effects of different pulsed electric fields on cell membranes, cytoplasmic matrixes, cell growth are introduced in this paper. Based on these effects, some applications of pulsed electric fields in cancer therapy, gene therapy, and delivery of drugs are reviewed in details.