Abstract: A Juvenile abalone shell length measurement method was introduced in this paper and the application of digital image processing method to measure the abalone shell length was described.The standard scale pixel length of the units was obtained by using specialized image analysis software (Image-pro plus) IPP 6.0, and then we got the pixel length of the abalone shell.By adopting unit calibration, the measurement value of the abalone shell was obtained which compared with the measurement values obtained by using calipers.By comparing the 13batches of 430abalone shell length data, the experimental results had good consistency and showed that the shell length measurement of abalone images based on digital image processing method had the characteristics of non-contact, high precision, fast measuring speed and the measuring results could be recorded directly to facilitate data statistics and analysis.Image measurement method could meet the needs on the actual production.It was also expected to be used for the detection of the crab, shellfish and other aquatic seedling size.