The application discloses a master control feedforward construction method of a boiler in a thermal power generating unit. The master control feedforward construction method comprises the following steps of performing subtraction on a calculated temperature value and a measured temperature value of a furnace exit of the boiler to obtain a temperature deviation value of the furnace exit; performingdifferential operation on the temperature deviation value of the furnace exit to obtain a first master control static feedforward basic component; acquiring a second master control static feedforwardbasic component corresponding to a power command; correcting the second master control static feedforward basic component by utilizing a current lower coal heating value to obtain a third master control static feedforward basic component; performing summation operation on the first master control static feedforward basic component and the third master control static feedforward basic component toobtain the master control static feedforward quantity of the boiler; acquiring the master control dynamic feedforward quantity of the boiler according to the power command; and performing summation operation on the master control static feedforward quantity and the master control dynamic feedforward quantity to obtain a master control feedforward signal of the boiler.