A method for determining pectin content in a plant sample includes: 1) adding an acidic alcohol solution to the plant sample, heating in a water bath and filtration; 2) soaking residue from step 1 with an acidic solution, heating in a water bath, a second filtration, bringing to volume after cooling and obtaining filtrate; 3) adding an acetic acid/sodium acetate buffer solution to residue of step 2, adding a pectinase solution, heating under vibration in a water bath, and a third filtration to obtain a filtrate; 4) adding an acetic acid/sodium acetate buffer solution and a pectinase solution to filtrate from step 2, heating the mixture under vibration in a water bath to obtain an enzymatic hydrolysate, adding filtrate obtained in step 3 to the enzymatic hydrolysate, bringing to volume, and obtaining a test solution; 5) drawing the test solution into a continuous flow analyzer to perform analysis.