<p>Understanding the mechanisms that influence the formation of stereocomplex crystals (SCs) in poly(lactic acid) (PLA) is critical for achieving effective regulation of SC content. In the current simulations, we constructed polymer blends with different initial chain conformations and then obtained four groups of polymer blend systems with similar segment miscibility but different chain extension degrees by controlling the high-temperature relaxation time. The simulation results indicate that the fraction of SCs formed in these systems is closely correlated with the average mixing parameters during the crystallization process rather than the initial chain extension degrees. In other words, the average segment miscibility in the crystallization process is the key factor controlling the formation ability of SCs.</p>