A high-precision weighing unit of electronic balance is designed by using DSP TMS320VC5502 for information processing.The weighing measurement principle of electronic balance is introduced and a data acquisition circuit based on DSP is given.The weighted recursive average filtering algorithm is adopted to guarantee measurement accuracy and stability.A multiple-level threshold discrimination algorithm is set up for judging change of weighting data

and the response time to the weight changes is improved.The weighing unit of electronic balance with this method has been proved to be steady and sensitive.It meets the design requirements.The range is 210g

the precision is 0.1mg

and the maximum permissible error（MPE）is less than 0.3mg.