The processability of ultrahigh molecular weight polyethylene (UHMWPE) improved by oligomer-modified calcium carbonate (CaCO3) was observed in our previous work. In order to understand the effect of oligomer-modified CaCO3 on the crystallization of UHMWPE, the non-isothermal crystallization behavior and crystallization kinetics of UHMWPE composites filled by oligomer-modified CaCO3 was studied by differential scanning calorimetry in this work. Jeziorny and Mo methods were used to describe the non-isothermal crystallization kinetics of UHMWPE composites.The effect of modified filler content and cooling rate on the crystallization temperature and crystallization rate was discussed. The heterogeneous nucleation of modified CaCO3 slightly increases the crystallization temperature of UHMWPE. The crystallization enthalpy of UHMWPE composites is significantly higher than that of UHMWPE. The crystallization rate of UHMWPE composites depends on the filler contents and cooling rate.