The invention discloses a method and system for processing a signal having high dynamic range. The method comprises the following steps of: obtaining the type of an electric-optical conversion curve of the signal having high dynamic range; obtaining the maximum brightness information in metadata of the signal having high dynamic range; setting the corresponding output value of the maximum brightness information in the electric-optical conversion curve to the maximum brightness value of the signal; intercepting an original curve section in the electric-optical conversion curve of the signal having high dynamic range, and setting the output value of the original curve section to be from zero and the maximum brightness value of the signal; if the brightness in need of being reached is a mapping brightness value, setting a ratio of the mapping brightness value to the maximum brightness value of the signal to a mapping coefficient; and, under a condition that a horizontal coordinate is constant, performing constant proportional mapping of the output value of the longitudinal coordinate of the original curve section according to the mapping coefficient so as to form a mapped electric-optical conversion curve section. The system comprises a gamma calling module, a dynamic mapping module and a gamma correcting module. By means of the method and the system disclosed by the invention, the problems that the HDR signal is relatively dark overall and the needed brightness cannot be reached can be solved.