In view of extraction process, the principles, the extracted effects and extracted time attributions of the main algorithms about the moving object extraction （MOE） from video pixel domain are analyzed and compared. The contributions lie in the selection rules of the appropriation algorithm for own uses according to different conditions. Simulation results are demonstrated，which are conducted on Hall-Monitor sequence. Then，a improved MOE algorithm is presented，which is based on frame difference and background subtraction simultaneously. Its robustness can deal with some complicated situations such as light change，the paused moving object in background and the uncovered background.