Conventional absolute phase extraction techniques typically require multiple frames of additional coded patterns to assist in fringe order recognition，reducing the effectiveness of the projection. Therefore，an absolute phase extraction method based on normalized modulation demodulating is proposed in this paper. Firstly，the space division multiplexing technology is used to establish a lookup table that specifies a unique code word sequence that corresponds one-to-one with the fringe order. Then，the phase-shifting sinusoidal fringes are used as carrier frequency fringes to directly modulate the code word to the amplitude intensity to form a space division multiplexing composite phase-shifting fringes. When the group of composite phase-shifting fringes is projected onto the measured object，both the wrapped phase and the modulation can be simultaneously demodulated from the captured composite deformed patterns. Normalization of the modulation can effectively suppress the influence of uneven reflectivity and demodulate the four grayscale codewords that can locate the fringe order，achieving absolute phase extraction without the need for any additional coding patterns. In order to improve the robustness of multi-level grayscale codeword extraction，the image morphology processing operations are utilized to segment the grayscale of the modulation，and a half-cycle connected domain codeword correction method is also proposed. The experimental results validate the feasibility and effectiveness of the proposed method.