A screen brightness adjustment method includes determining target brightness, determining a quantity of pixel rows controlled by each pulse in an emission (EM) signal required for implementing the target brightness, adjusting a pulse width of a pulse in a current EM signal based on the quantity of pixel rows controlled by each pulse in the EM signal required for implementing the target brightness to change a duty cycle of the EM signal, where the duty cycle reflects a quantity of pixel rows that are lit up and controlled by the EM signal.