The invention relates to a seawater base fracturing fluid which comprises a seawater base fluid, a gel breaking agent equivalent to 0.1-0.8% of the weight of the seawater base fluid, and a cross-linking agent equivalent to 0.2-0.8% of the weight of the seawater base fluid, and is characterized in that the seawater base fluid comprises the following components in percentage by weight: 0.3-0.6% of a thickening agent, 0.1-1% of a discharge aiding agent, 0.5-3% of a clay stabilizing agent, 0.01-0.1% of a sterilizing agent and the balance being seawater; the gel breaking agent is ammonium persulfate or sodium persulfate; the cross-linking agent is aluminum chloride or zirconium acetate; the clay stabilizing agent is potassium chloride or ammonium chloride; the discharge aiding agent is dodecyltrimethylammonium bromide or cetyltrimethylammonium bromide; and the sterilizing agent is methanal or dodecyl dimethyl benzyl ammonium chloride. The seawater base fracturing fluid has the advantages that the salt tolerance of the seawater base fracturing fluid is outstanding and stable cross-linking can be achieved in a weak alkaline environment.