<p>The velocity of pigging robots constitutes a critical determinant of their functional performance. The conventional mechanical bypass regulation mechanisms suffer from elevated fabrication costs, structural complexity prone to malfunction, and potential secondary pipeline damage caused by detached rigid components. This study proposes a heart valve-inspired soft bypass that demonstrates lower manufacturing costs, rapid response characteristics, and damage containment properties. This investigation employs the Coupled Eulerian–Lagrangian (CEL) method to develop a fluid–structure interaction (FSI) model, simulating both the hydrodynamic deformation of soft bypass and the dynamic behavior of the pigging robot equipped with soft bypass. Through analysis of the maximum stress and opening percentage during soft bypass deformation, the geometric parameters of the soft bypass were optimized. The motion characteristics of pigging robots with soft bypass were investigated. An air pushing experiment was performed on the soft bypass, employing the soft sensor for deformation measurement. Experimental results demonstrated differential response characteristics: the front bypass exhibited partial opening under air pushing, while the posterior bypass showed distinct closure behavior. This study presents a heart valve-inspired soft bypass. Providing a novel approach for velocity modulation in pigging robots.</p>