The　effects　of　prestrain,　connecting　strength,　and　the　wall　thickness　of　pipe　coupling　made　of　Fe-Mn-Si-C　shape　memory　alloy　on　the　connected　strength　of　pipe　couplings　were　investigated.　The　semifinished　pipe　couplings　were　cut　from　the　ingot　and　machined　into　pipe　couplings　with　varied　internal　diameter　and　wall　thickness.　The　pipe　couplings　were　heated　to　the　973　K　for　10min,　followed　by　a　water　quench.　The　contacting　area　was　increased　with　the　increase　in　the　connecting　length,　which　caused　the　tensile　load　increase.　It　was　analyzed　that　the　true　contacting　area　could　be　reduced　due　to　the　surface　inhomogeneity　increase　during　the　connecting　length　was　larger　than　a　specific　value.　The　connecting　strength　was　increased　with　the　increase　in　connecting　length　and　then　decreased　as　the　connecting　length　increased　further.　Results　show　that　the　connecting　strength　was　increase　with　the　increase　in　the　thickness　of　the　coupling　wall　and　the　stiffness　and　the　strength　of　the　coupling.