There are many vertical production layers in Penglai block in central Sichuan, and weak plane structures such as faults and fractures lead to complex pressure system and high well control risk. There are many difficulties in the geological engineering of long well section, such as hole pressure sticking, overflow and span leakage, and complex accidents occur frequently, especially serious formation leakage and inaccurate prediction of leakage pressure, which lead to unreasonable allocation of mud density and high incidence of drilling accidents. Therefore, on the basis of describing the leakage mechanism, combining drilling density, engineering parameters, leakage velocity, leakage amount and other parameters, this paper determines the prediction model of each layer’s leakage type and leakage pressure, establishes the calculation model of regional leakage type and leakage pressure, and applies it to drilling engineering design and on-site plugging basis. The practice proves that the stratified leakage pressure model can effectively avoid the occurrence of drilling leakage accidents. After modifying the parameters of the leakage pressure model and adjusting the density of drilling fluid, the leakage situation can be improved rapidly.