To explore the catalytic synthesis process of chlorchalcone and its flavones with different substitutions using paeonol as precursor, and to explore a new way to synthesize chlorchalcone and its flavones. ChalconeⅠ, Ⅱ and Ⅲ were synthesized by paeonol and chlorobenzaldehyde catalyzed by Clason-Smit reaction base, and then the chlorobenzone Ⅳ, Ⅴ and Ⅵ were synthesized by iodine catalytic cycloclosure of the three chalcone respectively. ₁^{H NMR,} ₁₃^{CNMR, 135°DEPT, FTIR} and UV and fluorescence properties of the products were tested. The yield of chlorinated flavonoids Ⅳ, Ⅴ and Ⅵ were 88.6%, 87.7% and 86.1%, respectively. The fluorescence intensity at the fluorescence peak (λ_ex/ λ_EM) 220/415 nm was 400, 500 and 600, respectively. The synthesis of chalcone Ⅰ is the key step. Taking the synthesis of chalcone Ⅰ as an example, the effects of single factors such as base, temperature and solvent on the yield of chalcone were investigated, and the synthesis process conditions were optimized by response surface method. With benzaldehyde dosage of 3.6 mmol, paeonol 3 mmol, ethanol 15 mL, NaOH 0.239 g and reflux at 70 ℃ for 10 h, the yield of chalcone Ⅰ was up to 93.7%. Under the same conditions, the yield of chalcone Ⅱ and chalcone Ⅲ was 92.3% and 92.1%, respectively. The synthesis process of chlorinated chalcone and flavone is simple, green and environmentally friendly, and can achieve