Abstract: To eliminate the signal trend terms, wavelet base functions are introduced for signal decomposition and reconstruction. The selection of wavelet bases may affect the result of eliminating signal trend. The concept of error index of signal trend elimination was proposed and the formula for calculating the index was presented. Using this formula, the error indexes of signal trend elimination of 34 types of wavelet bases were calculated. It was found that the wavelet bases of sym10 and other 5 types could be selected as preferred ones with less error indexes of signal trend elimination. Further, the sym10 and other two non-preferred wavelet bases were used to carry out the signal trend elimination of measured car body acceleration signal. The result shows that wavelet base of sym10 extracts the signal trend more precisely than other two non-preferred wavelet bases and the effectiveness of the presented formula for calculating the error index of signal trend elimination is validated.