Carbon　steel　and　low　alloy　steel　are　pearlitic　heat-resistant　steels　with　a　lamellar　microstructure.　There　are　good　mechanical　properties　and　are　widely　used　in　crucial　components　of　high-temperature　pressure.　However,　longterm　service　in　high-temperature　environments　can　easily　lead　to　material　degradation,　including　spheroidization,　graphitization,　and　thermal　aging.　This　study　proposes　a　theoretical　model　of　ultrasonic　backscattering　with　a　lamellar　structure　in　pearlite　areas.　It　analyzes　the　effects　of　different　pearlite　area　ratios　and　interlamellar　spacing　on　ultrasonic　backscattering　signals.　A　Voronoi　diagram　is　used　to　constructs　a　two-dimensional　finite　element　(FE)　model　of　the　lamellar　structure,　and　the　effects　of　different　pearlite　area　ratio　and　interlamellar　spacing　on　the　backscattering　signals　are　analyzed　to　verify　the　correctness　of　the　theoretical　model.　By　preparing　spheroidization　samples　of　various　grades,　the　change　values　of　pearlite　area　ratio　and　interlamellar　spacing　are　measured.　The　backscattering　signals　of　different　spheroidization　samples　are　collected　through　the　ultrasonic　testing　experimental　platform,　and　the　root-mean-square　(RMS)　maximum　values　of　the　ultrasonic　backscattering　are　extracted.　The　observed　trend　is　consistent　with　the　theoretical　model,　finite　element　method　(FEM),　and　experimental.　Compared　with　the　experimental　results,　the　model　results　have　some　errors,　but　can　be　used　to　evaluate　the　performance　degradation　of　metallic　materials　with　lamellar　pearlite　structure.