The invention discloses a rapeseed peptide for reducing blood pressure, preparation method and applications thereof. The preparation method is as follows: firstly, mixing degreased rapeseed cake with water, adjusting pH value, extracting, centrifuging, settling, extracting again, combining supernatant, adjusting the pH value to settling protein, separating the supernatant, adjusting the pH value of the supernatant to conduct the secondary protein settlement, abandoning the supernatant, combining the settlement, washing the settlement by deionized water, adjusting the pH value, stirring so as to dissolve the settlement, and then cooling and drying, thus obtaining rapeseed protein; and secondly, dissolving the rapeseed protein in distilled water, adding alcalase for hydrolysis, then adding flavourzyme for hydrolysis, killing enzyme, cooling, then obtaining the supernatant by centrifuging, cooling and drying the supernatant, thus obtaining the rapeseed peptide for reducing the blood pressure. The invention has the following advantages: the alcalase and the flavourzyme are utilized for hydrolysis, the hydrolysis degree is improved effectively, the bitterness of the rapeseed peptide is reduced, simultaneously, the rapeseed peptide with richer low molecular weight peptide and blood pressure reducing activity can be obtained. Furthermore, the condition is moderate, the flow is simple, the energy consumption is low, and the industrial production is easy.