Abstract: Described in the paper is an unconventional measurement method for sectional parameters of the etch test specimen，i.e.，the computer software measurement method，covering design of program modules for preprocessing of etch specimen image，software measurement of width，depth，excess metal，pool width ratio and pool depth ratio of both outer and inner welds，and measurement principles for side angles and deviation and overlap of outer and inner welds，etc. The newly-developed measurement system will enhance operation accuracy and convenience，and storage capacity of specimen data，shorten time for etching and grinding of the specimen，and solve problems like large error.