The invention provides a method and a device for optimizing a direct transaction mode between a generating unit and a power consumer. The method comprises the steps of firstly determining all direct transaction modes between the generating unit and the power consumer; then determining wind-solar power abandoning quantity of a new energy generating unit or the sum of economic costs of the wind-solar power abandoning quantity and a thermal power generating unit under all direct transaction modes; and finally selecting the direct transaction mode with minimum wind-solar power abandoning quantityor the minimum value of the wind-solar power abandoning quantity and the economic cost as an optimal direct transaction mode. Different direct transaction modes are finally provided and optimization of different direct transaction modes is realized. The invention provides a direct transaction optimization model, compared with all direct transaction modes, the new energy consumption capability is improved and the economic cost of the thermal power generating unit is reduced.