Abstract: Using the tensile curve of metastable materials,a method for measuring transformation energy (Ept) of strain-induced martensite and increment of transformation-induced plasticity was proposed by extrapolating hardening curve of austenite.Ept and the averaging plasticity increment (P value) was tested at -196 ℃ using a CrNi series austenite stainless steel as an example.The results show that per unit volume fraction Ept keeps a constant value of 11.3×106 J·m-3 in the stages of elasto-plasitic instability and stress plateau.The averaging plasticity increment (P value) induced by transformation per unit volume fraction is 0.205%.