In this paper, a single direction quantitative image quality improvement method based on on-orbit MTF test is proposed to improve the image quality due to the phenomenon that the image quality of the TDI push-sweep optical remote sensing camera may decrease in along-track or vertical track. Firstly, the MTF curves in both directions were tested by the edge bar method. N different frequency points in the range from zero frequency to Nyquist frequency were selected to determine the MTF improvement multiple of each selected frequency point according to the ratio of the MTF target value to the measured value. The spatial convolution function was constructed according to the frequency domain response characteristics and the lift multiple was taken as the amplitude of the frequency domain response. At the same time, the noise suppression function is constructed based on the on-orbit measured signal-to-noise ratio (SNR), and the quantitative improvement of MTF is realized under the premise of ensuring SNR. According to the verification results of the on-orbit test, the image quality is improved according to the proposed method. Within the noise suppression threshold of 0.5 dB, the MTF of the vertical rail direction is basically unchanged, the MTF of the Nyquist frequency point along the rail direction is increased by 2.51 times, and the clarity of the obtained image is improved by 8.33%, which proves that the method can effectively achieve quantitative image quality improvement.