Carbon fiber reinforced polyetheretherketone (CF/PEEK), which has the advantages of high specific strength and specific stiffness, high impact resistance, and easy recycling, has gained massive attention in aerospace, automotive, marine, medical fields. As a high-performance semi-crystalline thermoplastic composite material, its mechanical properties are closely related to its thermoforming process parameters. The material undergoes complex thermodynamic processes during the thermoforming process, so it is crucial to study its crystallization process with an accurate and practical crystallization kinetic model. Existing theoretical models for non-isothermal crystallization of thermoplastic composites are often difficult to obtain the parameters and have the problem that the final relative crystallinity cannot reach 1. For this reason, this paper proposes an improved nonisothermal crystallization kinetic model for thermoplastic composites based on the Mampel model using a new segmented functional form to simplify the expression of the crystallization rate function K(T), and analytically validates the model on CF/PEEK thermoplastic composites.