Abstract: Symmetric finite impulse response (FIR) filter with astrictly linear phase characteristics and system stability is widely used in data transmission, image processing and other fields. Conventional digital filter based on single-point processing mode can process point signal in real-time. H owever, its processing speed is slow, and real-time performance is not very good when dealing with images, or voice frame signals. This paper proposes a block processing model to solve this problem. By analyzing FIR filter theory, a symmetric FIR filter was designed based on block processing mode, and implemented in the TMS320C5510 chip (a DSP chip). The filtering algorithm based on two-pointerscircular addressing was introduced, and the main program was given. Computer simulation shows that the block processing mode of the program significantly improves the processing speed of frame signal, and filtering performance is satisfactory.