The invention relates to a macroblock layer rate control method based on an H264 video encoding standard. The macroblock layer rate control method comprises the following steps of: A, calculating a target bit number of a current frame by using a fluid blocking model and a linear tracing theory; B, distributing the bit number of a macroblock layer; C, predicting an average absolute error ratio of the current macroblock in the current frame; D, calculating quantization parameters of the corresponding macroblock; and E, realizing rate-distortion optimization of each macroblock in the current frame by using the parameter values obtained in the step D. The macroblock layer rate control method disclosed by the invention has the beneficial effects of enabling the generated error rate to be closer to the target error rate and improving the structural similarity of video output sequences, thereby obtaining better subjective video quality.