The　use　of　ultrasonic　arrays　to　characterize　defects　is　an　important　area　in　non-destructive　evaluation.　In　this　paper,　the　scattering　coefficient　calculation　model　of　the　defect　is　built　by　using　subarray　transmitter-receiver　pair.　Then　an　approach　of　crack　like　defect　characterization　based　on　the　scattering　coefficient　distribution　is　developed　in　the　light　of　study　on　the　relationship　between　scattering　coefficient　and　direction　of　defect.　The　full　focusing　image　from　the　full　matrix　capture　data　obtained　to　determine　the　location　of　the　defect.　Then,　scattering　coefficient　distribution　was　deduced　to　extract　the　information　on　the　crack　like　defect　orientation　by　dividing　the　linear　array　into　a　certain　number　of　subarrays.　Results　in　simulation　show　that　the　crack　like　defect　characterization　method　is　effective.