Based on X-ray diffraction (XRD) analysis, a method to approximately calculate the contents of phases was presented. Using this method, the contents of the three phases epsilon (hcp), gamma (fcc) and alpha' (bcc) in Fe-17Mn-5Si-10Cr-5Ni SMA after pre-straining were calculated and their relations with shape memory effect (SME) were analyzed. When pre-strain is less than 6%, the quantity of stress-induced epsilon -M and the recovery strain of the alloy increase with the growth of the pre-strain, In tested alloy only when pre-strain is more than 5%, alpha'-martensite appears and it is usually unfavorable to the SME.