This paper describes an IIR band-stop filter developed based on the STM32F103 microcontroller. The design details the process of setting filter parameters in MATLAB and how these parameters and original signal data are input into the microcontroller. The research work is divided into three parts: (1) generating filter parameters using MATLAB, (2) applying them on the STM32F103 module, and (3) outputting signal data via serial port. First, filter coefficients are generated through MATLAB and used as input for IIR filtering processing in the STM32 function; then the original data is processed using the IIR filtering function from the DSP library, with computation results stored in an array; finally, the filtered signal data is output through the serial port. Experiments demonstrate satisfactory filtering performance, with the IIR filter showing significant advantages in efficiency, transition band width, and computational complexity.