Abstract: In-pipe intelligent plug can fulfill high-pressure plugging operation inside the pipeline by means of wireless control system while the pipeline is in operation. In order to keep the plug operating safely and smoothly and reduce the effect of blocked flow field inside the pipeline on plugging operation, it is necessary to investigate the evolution laws of flow field and the force on the plug in the process of high-pressure plugging inside the pipeline. In this paper, the 3D model of inpipe intelligent plug was established to simulate numerically the flow field around the plug in the process of high-pressure plugging inside the pipeline by mass and momentum conservation equations. And accordingly, the relationships between the force on the plug vs. plugging schedule, inlet pressure intensity and inlet velocity were obtained. It is indicated from the evolution laws that different end faces have a certain effect on the characteristics of flow field and the force on the plug. Two kinds of end face shapes with the characteristic of pitch arc were proposed. The simulation reveals that in the process of plugging, the intelligent plug with the semi-spherical end face is superior to those with stepwise or paraboloidal end face in terms of the variation of flow field characteristic around the plug and the force on the plug. The research results provide the basis for the structural design and optimization of in-pipe high-pressure stable plugs. (11 Figures, 2 Tables, 28 References)