TMS320C6455 is a high performance digital signal processor (DSP) provided by Texas Instruments Corporation of USA. By using the low-cost C6455 chip as the core processor, a filtered back projection (FBP) based positron emission tomography (PET) image reconstruction algorithm is optimized and implemented in this paper. By specific effective optimization of algorithm and DSP code, the system can reconstruct a 512×512 PET image in 40 seconds, and achieve desirable image definition. The PET image reconstruction method based on DSP can be applied to the area of PET medicine image reconstruction and other related areas.