Abstract: The analysis of ΔLOD is of profound significance on climate forecasting,disaster prevention,deep space exploration,geodesy and other fields.With extremely high precision and angular resolution,VLBI plays the irreplaceable role on the analysis of the changes of the length of day.Based on this,the ΔLOD sequence and its precision are estimated from VLBI observations during 1985-2010 with comparison with the results published by IVS.The half-month,month,half-year,year periods and longer periods of the changes of ΔLOD is extracted with FFT and wavelet analysis.At the same time,the integration curve map of the ΔLOD is made to analyze the seasonal and long-term changes of earth rotation.At last,the causes of the changes of LOD are analyzed.