The invention provides a method and a device for processing data on the basis of modular exponentiation. The method includes storing module lengths n into first arithmetic registers and storing module numbers N into second arithmetic registers; acquiring modular results X of the module numbers N in the second arithmetic registers and storing the modular results X in third arithmetic registers; calling first modular addition arithmetic units to carry out modular addition operation on values of the third arithmetic registers, acquiring modular results Y of the module numbers N and storing the modular results Y into fourth arithmetic registers; calling modular exponentiation arithmetic units to carry out modular exponentiation on values of the fourth arithmetic registers, acquiring modular results Z of the module numbers N and storing the modular results Z in fifth arithmetic registers. Modular operation is carried out on the modular numbers N by values R to obtain the modular results X, and the values R meet an equation of R=2*n. Modular operation is carried out on the module numbers N by values 2*R to obtain the modular results Y. Modular operation is carried out on the module numbers N by values R*R to obtain the modular results Z. Power exponents of the modular exponentiation arithmetic units are values of the first arithmetic registers, power base numbers of the modular exponentiation arithmetic units are the values of the fourth arithmetic registers, and module numbers of the modular exponentiation arithmetic units are values of the second arithmetic registers. The method and the device have the advantage that the data processing efficiency can be improved by the aid of the method and the device.