Nanotwin structures can enhance both strength and ductility, but are amenable to detwinning caused by incoherent twin boundary (ITB) migration. While previous research treated the ITB as an array of Shockley partial dislocations, ITBs can deviate from this ideal model by either introducing Frank partial dislocations or changing misorientation angles. Using molecular dynamics simulations, we found both deviations lead to new migration behaviors. The Frank partials can be ejected out of the ITB moving by dislocation slip under high driving forces; as the driving force decreases, the ITB curves around the Frank partials and then is flattened by boundary sliding. Beviating the misorientation angle of ITB from its ideal coincident-site-lattice relationship removes a portion of its original grain boundary dislocations, leading to shear-coupled migration, while the migration of the original ITB under the same condition is not shear-coupled. Our findings deepen our understanding of the structure-migration-mechanism relationship for ITBs.