Abstract: In order to prepare a simulation source that can replace ¹³N(T_1/2=9.97 min) gas for direct calibration of ¹³N monitor, this paper adopts two-step wet gel preparation technology and CO₂ supercritical drying technology to carry out research on the preparation process of silicon-based aerogel. TEOS is used as raw material to prepare precursor solution. After the precursor system was prepared, add acetone 45 times of the precursor raw material to dilute it, and the gel was gelled at pH=8. After supercritical drying,the preparation of the aerogel matrix meeting the requirement is finished. Based on this process, a ²²Na (T_1/2=2.60 a) gas simulation source was developed for calibration of a ¹³N monitor with a density of 4.6 mg/cm³ (4 times the air density), the intra-batch uniformity was 5%, and the inter-batch uniformity was 8%. A gas simulation source was used to calibrate the efficiency of a ¹³N monitor prototype, and there was a 25% relative deviation from the simulation results.