The present invention relates to an analytical method and device utilizing magnetic materials and acoustics sensor. The invention employs a magnetic material modified with specific recognizable molecules to capture a substance in a sample and provides an external magnetic field to draw the magnetic material to an sensing region of an acoustics sensor, and then converts an effect occurred on a surface of the sensing region to an amount of the substance in the sample, wherein the effect is caused by a contact of the surface with the magnetic material and the substance.