Changing the variable-length code to equal-length code is required in feature match process of conventional algorithm based on the zero-crossing of the wavelet transform first proposed by Boles. But the factor for the variability of the code length is complex

so through the process of compulsively changing the variable-length code to equal-length code

the final recognition rate will be influenced. Aiming at the above problem

an iris recognition algorithm based on zero-crossing position of wavelet transform and matching using variable-length code is proposed. After the zero-crossing positions of the wavelet transform at each level from the 4th decompose level to the 8th decompose level are calculated

a sort of shift-matching algorithm is used to directly calculate the distance of the variable-length code

the detailed process is that

the distance of the two samples is calculated at each relative shift has occurred

then the minimal distance is chosen as the distance of the two sample. In iris database containing 800 images

experimental results show that the recognition rate of this method reaches 97.70％

about 5.16％ higher than that of Boles’ method

while the feature extracting time and the match time is only 0.2s. It can satisfy the system requirements of the capability of real time in iris recognition system.