The invention relates to an online updating method for image compression dynamic regulation, in particular to dynamic regulation of the image compression achieved by dynamic calculation, modification and quantification of a coefficient QP in a wireless image transmission system. According to an H.264 international standard, intra-frame predicdion and inter-frame prediction are conducted to YUV images, correlative compression of space and time is realized, and a QP value of key reference frames of an image sequence is calculated according to image content information. According to difference information of the key reference frames and the other frames, energy threshold values of the other frames are calculated, and the QP values of all frames in the image sequence are determined. According to the QP values of all frames in the image sequence, the image sequence is quantified and image coding compression is completed. According to the online updating method for the image compression dynamic regulation, video dynamic compression of the coefficient QP is dynamically modified and quantified according to the image content information, and online updating of image compression bit rate in the wireless image transmission system can be completed.