The invention discloses an operation optimization decision-making method for a gas-steam 
combined cycle unit, and belongs to the technical field of 
gas turbines. The operation optimization decision-making method for the gas-steam 
combined cycle unit comprises the following steps: step 1, mining and 
processing data in a 
distributed control system of the gas-steam 
combined cycle unit, and summarizing effective operation data; step 2, decomposing layer by layer based on a calculation relationship and a mechanism relationship of the operation parameters of the gas-steam combined cycle unit, and carrying out classification 
processing on the effective data; step 3, combining the classified effective data, and carrying out calculation 
processing by utilizing a performance calculation principle and a consumption 
difference analysis principle; step 4, drawing the optimal 
operation mode graph or curve graph according to a calculation result; and step 5, feeding back to an operation center through an information network to assist the unit to optimize operation. According to the invention, the performance state of the unit is monitored in real time, the optimal operation curve is sought through the performance and consumption 
difference analysis and calculation, and the safe and efficient operation of the unit is guaranteed.