The　effects　of　lamellar　structure　on　deformation　and　fracture　behavior　in　a　Ti-48Al-2Mn-2Nb　alloy　produced　by　centrifugal　spray　deposition(CSD)　were　investigated.　The　deformation　and　fracture　of　samples　after　tensile　and　compressive　tests　were　examined　in　a　scanning　electron　microscope　(SEM).　The　in　situ　tensile　testing　was　further　carried　out　in　a　SEM　and　the　crack　growth　path　of　samples　was　observed.　The　result　shows　that　there　is　a　remarkable　effect　of　lamellar　structure　of　CSD　TiAl　alloy　on　its　deformation　and　fracture　process.　Especially,　the　main　crack　extension　is　dependent　on　the　lamellar　direction　relative　to　tensile　loading　axis.　SEM　observations　indicate　that　there　is　a　shielding　toughening　effect　of　lamellar　structure　on　fracture　in　CSD　samples,　such　as,　crack　deflection,　crack　path　tortuousity,　and　crack　branching,　etc.　Moreover,　the　crack　growth　path　shows　that　the　main　crack　grows　tortuously　and　uncontinuously　by　ligaments　bridging　many　microcracks　in　front　of　crack　tip.　The　effect　mechanism　of　microstructure　on　deformation　and　fracture　process　is　discussed.