The Automatically picking sudden commencement (SC) and the generation of report is a pressing problem in data production in the Geomagnetic Network of China (GNC). A method based on Walsh transform and Akaike Information Criteria (AIC) is proposed in this paper which focuses on solving the problem of high-precision SC picking in 1-second resolution data,so-called Walsh-AIC method. A comparative study with other popular methods was conducted by using 98 horizontal components of magnetic data. The SC menu provided by International Service of Geomagnetic Indices (ISGI) is adopted as a standard. The picking precision of Walsh-AIC method is better than that of others through comparison including standard deviation and average deviation. Our method is suitable for automatic picking of SC.