Abstract: Disclosed is method of amplifying and labeling mRNA sample for the mRNA microarray. The invention utilizes the specific synthesized single strand oligonucleotide (ssDNA) poly-T to hybridize the complementary poly-A in the tail of the mRNA; converts the hybridized mRNA to the cDNA; hybridizes the mRNA detection probe on the mRNA microarray chip with the cDNA; amplifies the hybridized cDNA through extending the polymer based on the ssDNA; labels the amplified cDNA by integrating the fluorescent modified nucleotide into the amplified duplex oligonucleotide during polymer extension; verifies the amplified labeled cDNA through detecting the fluorescent signal. The fluorescent signal from the mRNA detection probe spot on the mRNA microarray chip will indicate the presence of the detected mRNA and the quantity of the fluorescent signal from the mRNA detection probe sport will be directly proportional to the amount of the fluorescent modified nucleotide in the amplified duplex oligonucleotide.