Ultrasonic　non-destructive　testing　method　was　introduced　to　detect　flexible　package　seal　quality.　The　channel　defects　with　diameters　of　between　50　and　150　μm　in　the　seal　area　of　flexible　package　were　detected　using　Backscattered　Echo　Envelope　Integral　(BEEI)　imaging　method.　The　echo　signal　for　each　scan　point　in　time-domain　was　Hilbert-transformed　to　produce　its　envelope,　and　was　further　integrated　over　the　entire　signal　envelops　to　obtain　the　BEEI　value.　The　BEEI　value　was　calculated　producing　a　two-dimensional　BEEI-value　matrix.　The　matrix　was　aligned　into　a　rectilinear　pattern　mapped　at　the　scan　pattern　grid,　and　then　was　interpolated.　The　final　interpolated　matrix　was　used　to　yield　the　gray　scale　image.　The　images　were　formed　with　a　spot　focused　22.66　MHz　ultrasound　transducer　scanned　over　a　2.98　mm　×　1.50　mm　rectangular　gird.　Coefficient　of　variation　(CV)　values　of　BEEI-matrix　for　each　sample　were　studied.　The　variations　of　the　BEEI　values　in　the　direction　vertical　to　the　edge　of　the　heat　seal　and　in　the　direction　parallel　to　the　edge　of　the　heat　seal　were　compared.　The　results　show　that　channel　defects　and　inclusion　defects　in　flexible　package　can　be　effectively　detected　using　BEEI　imaging　method.　The　CV　values　are　lower　than　8%　for　channel　and　inclusion　defect,　which　indicate　the　variation　of　the　BEEI　values　in　matrix　is　small.　The　mean　BEEI　values　on　the　defect　region　are　about　greater　between　30%　and　40%　than　that　on　the　background　region.