Abstract: Singleframe phase demodulation algorithms for fringe pattern are widely employed in realtime and dynamic measurement techniques. Subfringe integration(SI) algorithm has an advantage of strong antinoise ability. However, the period estimation of the deformed pattern using the carrier frequency would result in frequency mismatch. Against the inherent defect, an improved algorithm was proposed. The proposed algorithm estimated the local frequency, and then computed the intensity integration for phase extraction. Results show that the phase error of the new algorithm is one third of the original algorithm in simulations. The finge projection profilometry experiment was also conducted to demonstrate the validity of the proposed algorithm. This papar provides a candidate for singleframe fringe phase analysis technique.