The 2-D transition metal dichalcogenide (TMD) semiconductors, has received great attention due to its excellent optical and electronic properties and potential applications in field-effect transistors, light emitting and sensing devices. Recently surface plasmon enhanced photoluminescence (PL) of the weak 2-D TMD atomic layers was developed to realize the potential optoelectronic devices. However, we noticed that the enhancement would not increase monotonically with increasing of metal plasmonic objects and the emission drop after the certain coverage. This study presents the optimized PL enhancement of a monolayer MoS 2 in the presence of gold (Au) nanorods. A localized surface plasmon wave of Au nanorods that generated around the monolayer MoS 2 can provide resonance wavelength overlapping with that of the MoS 2 gain spectrum. These spatial and spectral overlapping between the localized surface plasmon polariton waves and that from MoS 2 emission drastically enhanced the light emission from the MoS 2 monolayer. We gave a simple model and physical interpretations to explain the phenomena. The plasmonic Au nanostructures approach provides a valuable avenue to enhancing the emitting efficiency of the 2-D nano-materials and their devices for the future optoelectronic devices and systems.