Objective: To determine the extract from Radix Astragali. Methods : Astragaloside IV in extract from Radix Astragali was determined by TLC-Scanning. Results : The linear relationship was at the rang of 0.78 ?g~ 4.68 ?g. The average recovery was 99.06% ( RSD=1.17% and n =5). Conclusion : The method is available with a good reproducibility. The pretreatment is simple and easy to operate.