Three-dimensional polyacrylamide gel microarray (3-D gel microarray) has a strong adsorption for hybridzation probes with fluorescent label, resulting in high fluorescent background noise. The background noise has hampered the broad application of the microarray in scientific research. A low-frequency ultrasound of 40 kHz has been successfully employed to efficiently remove the nonspecifically bound fluorescent probes from the 3-D gel microarray. The method can significantly enhance the signal to noise ratio of the 3-D gel microarray and make it work better in single-nucleotide polymorphism genotyping.