Morlet wavelet, which has the good localization characteristics both in the spatial and frequency domain, is commonly used to demodulate the phase map of the fringe pattern in wavelet transform profilometry by calculating the similarity between parts of the fringe pattern and the wavelet function. The phase information can be extracted by finding out the“ridge”information of the wavelet transform coefficients. Furthermore, the reconstructed surface of the tested object is obtained by the extracted the phase information and combining the system parameters of the measurement system. However, when the wavelet “ridge” method is used to demodulate the phase map, a first-order Taylor approximation is introduced to deduce the phase analytical description of the deformed fringe from the wavelet coefficients at the“ridge”position, which causes a big phase error in the areas with high height variation rate. Aiming at the shortage of the method, an improved Morlet wavelet transform“ridge”method based on a second-order Taylor expansion is presented. The detailed phase analytical expression from the wavelet transform coefficients at the position of“ridge”is given as well. Compared with the conventional wavelet “ridge” method employing the first Taylor approximation, the improved method has higher accuracy, especially around the zone with higher height variation rate, because a correction related to the second derivative of the tested object is introduced. Computer simulations and experiments verify our analysis.