Shallow Water Flow(SWF)as a kind of geologic hazard is common in riserless drilling of deepwater shallow layer, and it is proved that riserless pilot hole drilling technology with DKD system is an effective method to deal with this issue. In this paper, the analysis of suitability was given by studying the riserless pilot hole drilling technology characteristics to the layer with SWF. The equilibrium equation; continuity equation; motion equation and auxiliary equation were established based on the oil well fluid mechanics and porous medium fluid mechanics. The calculation and comparative analysis with this hydraulic parameter calculation was conducted on W-X01 well in South China Sea. The results show that the key factors of construction control when riserlesss drilling is drill fluid displacement; drilling rate and drill pipe rotation rate, and the annuli pressure loss which will affect the bottom hole pressure will change by controlling these there parameters. The annuli pressure loss will increase with the increase of drill fluid delivery rate, and it will obtain more sharp increasing trend when the wellbore is small, and also it will increase as the drill pipe rotation rate increases. The method could be used as a guideline when designing and conducting a riserless pilot hole drilling in deepwater layer with shallow water flow.