Nanoparticle, preparation method, calculus removing device, magnetic target separation instrument and application. The nanoparticle includes the kernel being made of magnetic material, and coating material monomer is connected to the shell that the kernel is formed by initiator and/or crosslinking agent. Obtained nanoparticle can wrap up the calculus in urinary system, then under the action of magnetic target separation instrument, it is not damaged quickly to take out the tiny calculus of internal remaining in vitro, ureter wall is not damaged when dragging calculus, is placed convenient and is not easily caused calculus to shift.
