Abstract: A novel rate adaptive control algorithm is proposed based on study of JPEG2000 rate control algorithm. After wavelet transform, the coefficient is modeled as Gaussian distribution, but remove the offspring of the lowest frequency. Each block bit rate of the actual encoding has been achieved based on rate-distortion theory in the overall rate certain, and the bit rate should be real-time deadline in the entropy coding. The offspring of the lowest frequency has been code at without distortion. This algorithm achieve bit rate deadline in real-time, reducing the encoder computation and memory usage. Experimental results show that after the removal of the most low frequencies, the remaining band coefficient modeled as a Gaussian distribution, the image compression is significantly better than results that the whole band is the Gaussian distribution, when the compression rate is not too high(>0.5bpp). And rate allocation algorithm is accurate and low complex, and that it is most suitable for hardware implementation.