The invention provides a nuclear pulse signal processing method based on RC inverse transformation. The method comprises the following steps that S1) distributed capacitance and resistance which have influence on a negative-index nuclear pulse signal in a preamplifier circuit are equivalent to an RC circuit; S2) an RC circuit differential value analysis method is used to obtain a function expression of the negative-index nuclear pulse signal and a double-index nuclear pulse signal; S3) the double-index nuclear pulse signal is obtained via ADC sampling, used to calculate the rising edge recovered negative-index nuclear pulse signal via the function expression in the step 2); and S4) the rising edge of the rising edge recovered negative-index nuclear pulse signal and a falling edge of the double-index nuclear pulse signal are used to form a new nuclear pulse signal. According to the invention, influence of the distributed capacitance and resistance on the rising edge of an output signal of the detector is eliminated, the rising edge recovered negative-index nuclear pulse signal is made trapezoid to carry out digital processing, the filtering and shaping effects of the nuclear pulse signal are improved, and the voltage measuring range of the system is broadened.