We report the impact of grafting glycidyl methacrylate (GMA) at different degrees onto isotactic polybutene-1 (iPB-1) on the crystallization process. The study of the crystal form transition using FTIR and X-ray Diffraction (XRD) revealed that the conversion degree from form II to form I of the grafted iPB-1 (iPB-g-GMA) was higher than that of iPB-1 under the same experimental conditions and increased with increasing grafting degree. The spherulitic size of iPB-g-GMA was smaller compared to iPB-1 at the same amplification factor in Polarized Optical Microscopy (POM). The kinetic parameters of the non-isothermal crystallization process have been determined based on Differential Scanning Calorimetry (DSC) experiments and the Ozawa and Mo equation. The results showed that the crystallization rate of iPB-g-GMA was higher than that of iPB-1. The activation energy for the non-isothermal crystallization process of iPB-g-GMA (with a grafting degree of 1.54%) was lower than that of iPB-1, which further illustrated that grafting GMA on iPB-1 accelerated the crystallization rate.