Abstract: Based on symbol dynamics in 1-D piecewise linear mapping chaotic systems, an arithmetic method processing chaotic signals is studied in the paper, including addition, subtraction and multiplication. The operational rules are calculated and proved according to a definition of the distance between two chaotic sequences. By computer simulation with convolution sum of FIR digital filter, the results show that the model is the same as traditional binary coding arithmetic, which can be used in chaotic signal processing systems.