Carboxymethyl chitin (CAS) and casein (CN) are prepared by ultrasonic method, and the Maillard reaction products (MRPS) are prepared by drying method. The effects of reaction temperature, reaction time and CN/CAS ratio on Maillard reaction are studied. The pH value, browning index, grafting degree, free amino number and Fourier infrared spectra are characterized. The final results show that the optimal reaction conditions are as follows: the Maillard reaction products with the final protein concentration of 10% reacting for 72 h have the highest reaction degree at 60 ℃, the relative humidity of 79%, the CN/CAS ratio of 5:4. The browning index is 0.697, the grafting degree is 70.09%, and the free amino content is 28.83%. The infrared spectra of CN, CN/CAS and MRPS indicate that carboxymethyl chitin (CAS) and casein (CN) have a Maillard reaction.