Nanoparticle measurement and collection is a challenging new frontier of science. Nanoparticle transport in an aerosol can take place by diffusion or under an external force field. Thermophoresis involves the movement of a particle under a thermal gradient. The review will understand the mechanism of thermophoresis, and how it affects nanoparticles of different sizes. Applications of theromophoresis to nanoparticle measurement will be reviewed.