Abstract: A new two dimensional phase unwrapping technique for fringe analysis is proposed and verified by experiments. The technique is based on the algorithms of weighted least square phase unwrapping using fast discrete cosine transforms and iterative methods, which were proposed by Ghiglia and Remero in 1994. Intensity modulation is calculated and used to create the weight matrix. Invalid areas of wrapped phase are weighted by small values. Thus their unfavorable effects on the final unwrapped phase map can be limited. The phase unwrapping process of fringe pattern can be achieved without any priori information or manual intervention. The iterative algorithms are proved to be highly robust.