Complex　working　conditions　and　state　of　charge　(SOC)　uneven　distribution　are　both　key　factors　inducing　the　performance　degradation　of　lithium-ion　batteries.　To　address　this　issue,　a　novel　distributed　thermoelastic　guided　wave　testing　technique　is　proposed　to　realize　the　SOC　distribution　testing　of　multi-regional　silicon　carbon　lithium-ion　batteries.　Since　the　ultrasonic　testing　method　can　acquire　the　changes　of　material　properties,　the　features　among　the　time　domain　signals　and　SOC　under　complex　working　conditions　(different　C　rate　and　temperature)　are　extracted　experimentally,　which　reveals　the　strong　correlation　between　the　acoustic　characterization　parameters　and　the　amount　of　cell　expansion.　Moreover,　the　theoretical　model　of　wave　propagation　in　multi-layered　porous　silicon　carbon　lithium-ion　battery　versus　temperature　is　built　to　depict　the　wave　mechanism.　It　is　constructed　by　state　vector　and　Legendre　polynomial　hybrid　method　in　the　context　of　Biot　theory　and　Green-Naghdi　theory.　By　comparing　the　experimental　and　theoretical　group　velocities　in　different　temperatures　and　SOC,　the　two　are　in　good　agreement.　It　verifies　the　validity　of　the　theoretical　model　and　experimental　method.　Subsequently,　the　proposed　thermoelastic　guided　wave　testing　method　is　used　to　determine　the　difference　of　the　time　domain　parameters　in　the　different　receiving　regions　and　SOC　evolution　stages.　The　results　indicate　that　the　acoustic　response　changes　significantly　in　different　regions　and　stages,　and　the　SOC　uneven　distribution　is　particularly　dramatic　in　the　low　SOC　stage,　and　the　response　becomes　more　sensitive　the　further　away　from　the　center　position　of　the　propagation　region.　The　connection　between　the　thermoelastic　guided　wave　behavior　and　the　SOC　make　it　possible　for　non-destructive　monitoring　of　the　silicon　carbon　lithium-ion　battery　SOC.　Our　proposed　method　is　beneficial　for　evaluating　the　potential　performance　degradation　due　to　SOC　uneven　distribution.