The invention discloses a microorganism through-put oil extraction method for a heavy-oil reservoir with a high water content, and a heavy oil viscosity reduction method for the heavy-oil reservoir with the high water content, and a nutrition activator, and belongs to the technical field of oil field chemistry. The microorganism through-put oil extraction method for the heavy-oil reservoir with the high water content comprises the following steps of: 1) injecting a water shutoff agent into an oil well; 2) then, injecting the nutrition activator, or injecting exogenous bacteria and the nutrition activator, and soaking; and 3) after the soaking is finished, carrying out production. By use of the microorganism through-put oil extraction method disclosed by the invention, before the nutritionactivator is injected into the oil well or the exogenous bacteria and the nutrition activator are injected into the oil well, the water shutoff agent is injected into the oil well for water shutoff, the amount of the nutrition activator and the exogenous bacteria injected into a water level can be reduced, and the cost of the microorganism through-put oil extraction for the heavy-oil reservoir with the high water content can be greatly reduced.