A sensitivity-enhanced optical pressure sensor based on molybdenum disulfide (MoS2) is proposed. The sensing principle is that the pressure causes the deformation of the polydimethylsiloxane (PDMS) pressure structure above the MoS2 film, leading to the change of the ambient refractive index, so that a measurable light propagation difference in the waveguide under the film is created to reflect the micro changes of the pressure. The pressure is finally numerically converted to the wavelength shift of the interference peak of the obtained spectrum. The process is simulated and analyzed using MoS2 dielectric film, in contrast with that using graphene dielectric film. It turns out that under same conditions, the MoS2 film has a more distinct modulation effect on light than that of the graphene film. Experiments using the real sensor prototype are carried out and the results show that the pressure measuring sensitivity is improved to 96.02 nm/kPa in the pressure range of 0-0.6 kPa, which is much higher than the typical optical pressure sensors. The proposed optical pressure sensor based on MoS2 is of high potential to support ultra-sensitive pressure detection in many applications.