The invention provides a quick time base correction device for a digital composite video signal. The device comprises a sampling module, a synchronous separation module, a time base correction analysis module, a first time reference correction module and a lagrange interpolation module, wherein the time base correction analysis module is used for calculating the length of the current row according to a horizontal synchronization head pulse signal, and comparing with a standard length according to the length of each row to acquire related deviation; the first time reference correction module is used for feeding the acquired deviation back to a step length after the acquired deviation is subjected to gain and ratio control processing; and the lagrange interpolation module is used for corresponding resampling according to the step length provided by the first time reference correction module to realize the extension or compression of the length of the whole row, making the accuracy of the adjusted step length one of 2m of a pixel point, and selecting a group of parameters from 2m groups of parameters, and performing corresponding lagrange interpolation according to the set parametersso as to complete the corresponding lagrange resampling operation. The device can effectively improve the adjustment accuracy.