Abstract: With the breakthrough of hydrocarbon exploration in the deep formations of the East China Sea, more and more drilling operations are targeting at the deep complex formations. Reservoir protection is especially important for the deep drilling due to the high rock strength, poor drillability, low ROP, poor porosity and permeability in reservoirs. This paper introduces MPD (Managed Pressure Drilling), a new kind of drilling technology, and analyses the technical advantages as well as the operation principles. In the drilling operation of Wells M4 and M5 located at Trap N of East China Sea, MPD were adopted and were successful, as demonstrated by significant increasing in the ROP and protecting oil and gas reservoir from formation damage. MPD provides a safe and efficient way for deep drilling in East China Sea.