In view of the problem that the display result of air combat situation is not intuitional and not convenient for use, a method for situation display and assistant decision-making based on Sudoku and the three-dimensional combat power field is given.This method uses combat power formula to calculate the power distribution on the situation plane, the improved down-sampling to calculate the average of the situation plane, and the TOPSIS and K nearest neighbor algorithm to calculate the relative threat level.Then, the recommended flight direction is given.Simulation result proved the validity of the method.The result of research shows that using Sudoku is helpful for situation display and assistant decision-making.