This paper presents results on the development and application of a three-dimensional (3-D) microstructure assembly technique-Plastic deformation magnetic assembly (PDMA). In PDMA, certain part of the microstructure to be assembled is plastically deformed by the magnetic force generated from the interaction between a magnetic material piece deposited on the microstructure and an external magnetic field. As a result, the entire microstructure can remain at a rest angle with respect to the substrate surface due to the plastic deformation. The amount of plastic deformation and the rest angle are found to he strongly dependent on the properties and the geometric parameters of the deformation region of the microstructure and also the magnetic material piece. A general design rule for PDMA has been given, PDMA is capable of batch-scale assembly. It has been successfully applied to fabricate novel micromachined devices with high yield and good controllability. As an example, the results of a novel vertical planar spiral inductor realized by the application of PDMA have also been presented in the paper.