Abstract: Heat gain and loss of the water transferred in a canal in winter is usually calculated using heat balance methods within the specifications. But when meteorological data is lacking, it is difficult to accurately calculate the amount of heat exchanged with the outside through heat balance factors, and the calculations always deviate from the real case. To solve the problem, we describe a novel method for calculation and analysis of the evolution of frazil ices through consideration of temperature changes in time and space and inverse calculation of the heat gain and loss of a water body from the measured water temperature. Application of this method to the frazil ices in water delivery canals in a cold region of Xinjiang shows that our calculations ? the average daytime temperature of -11 ?C and the canal ice output of 3.01 - 3.69 m3/s at night ? agree well with the calculations using empirical formulas and the relative errors are reduced to less than 8%. Our prediction of nearly no ice output in daytime was verified by the real operation of the canals. This indicates that the method considering temperature changes in time and space is more accurate than using heat balance factors and it is an improvement applicable to dynamic calculation and real-time, all-weather and full-process analysis on the formation, evolution and transport of ices in ice-water two-phase flow canals.