Liquid crystal polyarylate (LCP) possesses very low melt viscosity due to the rigid rod-shaped structure of its main chain, which is not beneficial for film processing and molding. The study aims to enhance the melt viscosity of LCP through blending modification with polytetrafluoroethylene (PTFE), while ensuring excellent mechanical properties, dimensional stability, and low dielectric performance at high frequencies. Rheological properties results of the blends indicate that the melt viscosity gradually increases with the addition of PTFE. Dielectric properties results of the prepared thin films indicate that the incorporation of PTFE significantly reduces the dielectric constant and dielectric loss of the blend films. The LCP/5%PTFE blend film possesses a dielectric constant of 3.15 and a dielectric loss of 0.013 5 under the condition of 1 MHz, representing a decrease of 7.1% and 24.9% compared to pure LCP. SEM images reveal that the incorporation of high-viscosity PTFE restricts the formation of the original long-range fibrous structure of LCP. Furthermore, thermal performance test results indicate that both the melting point and degradation temperature of the blends increase with an increasing proportion of PTFE in the blend.