Multigrid algorithm based on the transport of intensity equation is researched to retrieval phase information from the intensity measurement. Given initial value and stared from the coarsest grid, a solution is obtained by calculating; regarded it as the finest initial value, an approximate solution is obtained by calculating; then its residual is calculated and it is restricted to coarser grid and solving, until to the coarsest grid, followed by corrected the solution of finer grid. Finally, different frequency error components are eliminated by cycle which on different sizes grids, and the accurate solution is obtained. The simulation and real experiments show that the multigrid algorithm can well retrieve the actual phase of the object from the intensity image.