Provided is a siloxane dispersant having a structure including a head part having an affinity for nanoparticles and a tail part having an affinity for a polydimethylsiloxane (PDMS) resin, and a nanoparticle paste composition comprising the same. The dispersant significantly improves dispersion efficiency of a polydimethylsiloxane resin system which is used in preparation of high-output light sources such as UV LEDs and the like.