Gold nanorods have surface plasmon resonance (SPR) effect and own longitudinal plasmon resonance absorbtion (LSPR) peaks which can be tuned between visible and near infrared (NIR) zones. Moreover, because of SPR effect, gold nanorods also have photothermal effects which can transfer the energy absorbed from light into heat. And NIR light can penetrate into biological tissue with minimal lateral invasion. Therefore, gold nanorods are promising in the biomedical applications such as imaging, photothermal therapy and drug delivery and all of these applications can be controlled remotely by NIR light. And gold nanorods can integrate these functions into one platform, which can realize the combination of diagnosis and therapy, namely theranostics. This review introduces the basic properties of gold nanorods, summarizes three methods of surface modification, review the applications in two-photon fluorescence imaging, photoacoustic tomography imaging, optical coherence tomography imaging, X-Ray computed tomography imaging, photothermal therapy and drug delivery, and highlights latest progresses in application of theranostics.