To investigate the feasibility of using free fetal DNA from maternal plasma as the source of fetal material in non-invasive prenatal diagnosis, SRY gene of free DNA in maternal blood of 65 samples were analyzed by using primer extension preamplication (PEP) and probe microplate hybridization techniques. The results showed that the detection rate of SRY gene in maternal blood from women carrying male fetuses detected by probe microplate hybridization alone and probe microplate hybridization with PEP were 76.09% (35/46) and 95.65% (44/46) respectively, and there was a significant difference between them. The non-detection rate of SRY gene in blood samples from women carrying female fetus was 100% (19/19). It is indicated that probe microplate hybridization was an effective method in detecting trace fetal DNA from maternal plasma and the sensitivity could be substantially improved by combined use of the two techniques. Analysis of fetal DNA in maternal plasma can serve as an alternative for non-invasive prenatal diagnosis.