A novel multilayer photonic structure is proposed to achieve the strong enhancement of light absorption in monolayer molybdenum disulfide (MoS2). Both numerical and analytical results illustrate that the absolute absorption of light in this atomically thin layer can approach as high as 96% at the visible wavelengths due to the excitation of Tamm plasmon mode. It is also found that the operating wavelength and height of sharp absorption peak are particularly dependent on the layer thicknesses and period number of dielectric grating, MoS2 position in the spacer, and incident angle of light, which contribute to the tunability and selectivity of light-MoS2 interaction. These results would provide a new pathway for the improvement of MoS2 photoluminescence and photodetection.