The pearlitic transformation and the deformation behavior of lamellar cementite after cold rolling in eutectoid steels Fe-0.76%C-0. 137%Mn (mass fraction) were studied by means of Formastor-F (Full Automatic Transformation Testing Instrument) and field emission scanning electronic microscopy (FESEM) observation. Fine and coarse pearlite were obtained in the eutectoid steels austenitized at 900 ℃ for 15min, then hold at 620 ℃ for 90 s and 690 ℃ for 7 h, respectively. Thedeformation behavior of cold rolled lamellar cementite could be classified as: cleavage fracture, inhomogeneous slip, fragmentation, thinning or necking, and homogeneous bending. The cementite lamellae with the thickness of more than 100 nm could be deformed plastically.