The document discloses a pre-distorter, which comprises: a pre-distortion module, which is configured to pre-distort a plurality of baseband input signals by an equal number of pre-distortion functions to obtain an equal number of pre-distorted signals respectively, wherein all of the baseband input signals input into every pre-distortion function, and each pre-distortion function has one output; an adder, which is configured to combine all of the pre-distorted signals output from every pre-distortion function into one combined signal; and a power amplifier (PA), which is configured to amplify the combined signal, wherein the cascade of the pre-distortion functions and the PA are linear overall. And the document also discloses a method for distorting. The document reduces the implementation cost of a pre-distorter.