The influence of preheating adopted and preheating unadopted on manufacturing speed during the automated fiber placement process has been analyzed. According to Fourier heat equation and assuming the towpreg with uniform material properties, a heat transfer model of towpreg has been established. The boundary conditions and initial conditions of this model at different stages have been given based on energy exchange principle. The research chooses thermoplastic composite APC-2(carbon/PEEK) as the towpreg material and utilizes the finite element method to investigate the temperature history of the fiber placement process. Since fiber placement speed is related with the response time of temperature, it can be obtained by the temperature history. Finally, the results demonstrate preheating can significantly improve the fiber placement speed.