In order to quantitatively analyze the sugar and total sugar in corn accurately, this paper studied the determination method of sugar. Determine the extinction solution under different parameters. Such as the optimum determination wavelength, the amount of chromogenic agent, reaction time, settling time and acid hydrolysis time. In this paper, DNS method was used, and 3,5-dinitrophenol salicylic acid (DNS) was used as chromogenic agent. Brown-red amino compounds were reduced by heating under neutral or alkaline conditions, and then reduced to reducing sugar. The color depth was positively correlated with sugar content. The optimal experimental conditions were determined by single factor experiment, and the contents of corn and total sugar were calculated according to the specification curve of reducing sugar in glucose standard solution. The experimental results show that the best detection wavelength is 540nm, the dosage of chromogenic agent is 65438±0.5ml, and the chromogenic time is 5min. The linear density of glucose ranged from 8 to 40 ug/ml, and the total sugar solution was determined in parallel for 5 times, with RSD =1.1%; The average sample yield is 100.56%, RSD= 1.54%. It shows that this method is stable and reproducible. The infrared scanning spectrum analysis of the sample solution obtained by the system proves that the solution contains reducing sugar.