1. A method for estimating a body pose in a body pose detection module provided with a triaxial accelerometer within a wireless sensor network of a plurality of body pose detection modules arranged to detect and simultaneously monitor body poses of multiple users, the method comprising steps of: performing signal pre-processing of a triaxial acceleration signal readout from the triaxial accelerometer at the body pose detection module attached to a user body so as to abstract a dynamic acceleration and a static acceleration of the triaxial acceleration signal; determining whether the dynamic acceleration of the triaxial acceleration signal is abnormal indicating that a body pose is a falling pose; and when the dynamic acceleration of the triaxial acceleration signal is not abnormal, analyzing the dynamic acceleration of the triaxial acceleration signal to determine whether a body pose is one of a static pose and a dynamic pose, wherein the signal preprocessing is performed by: sampling from the triaxial acceleration signal readout from the triaxial accelerometer, each of sensing axes collecting 256 acceleration data, with a sampling frequency of 128 Hz and performing the signal pre-processing once at every two seconds; subjecting acceleration data of the sensing axes of the triaxial acceleration signal to an eight-layer Haar wavelet transform; maintaining a wavelet transform coefficient of the eight-layer Haar wavelet transform with a lowest frequency, while omitting other wavelet transform coefficients; converting the wavelet transform coefficient of the lowest frequency into a time domain to represent the static acceleration of the triaxial acceleration signal; and subtracting the static acceleration from the triaxial acceleration signal to obtain the dynamic acceleration of the triaxial acceleration signal.