The discovery of cell-free fetal DNA (cff-DNA) in maternal plasma offered a new way to noninvasive prenatal diagnosis for single gene disorders. In the past decade, many techniques such as real-time PCR, pyrophosphorolysis-activated polymerization, mass spectrum and digital PCR have been developed for noninvasive prenatal diagnosis. In this review, the author discuss the principles, applications, advantages and disadvantages of these techniques.