The disclosure provides an electrolyte supplement system in an aluminum electrolysis process, which includes low-molecular-ratio cryolite, wherein the low-molecular-ratio cryolite is selected from mKF.AlF3, nNaF.AlF3 or mixture thereof, where m=1˜1.5 and n=1˜1.5. When the electrolyte supplement system provided by the disclosure is applied to the aluminum electrolytic industry, electrolytic temperature can be reduced obviously in the aluminum electrolysis process without changing the existing electrolytic process; thus, power consumption is reduced, volatilization loss of fluoride is reduced and the comprehensive cost of production is reduced.