Abstract: The lift and drag characteristics of double-delta wing configuration is more ascendant than that of delta wing configuration. To seek for the optimized aircraft design scheme with numerical methods is firmly bottomed upon the engineering calculation of aircraft aerodynamics. By using the semi-experiential engineering arithmetic based on the ideology of area ratio, the slope of lift coefficient curve, the zero-lift drag coefficient and the induced drag factor of double-delta wing aircraft were calculated. Being compared and corrected by the data from wind tunnel tests, it is shown that the precision of calculated results quite meets the requirements of conceptual aircraft design. The arithmetic has been successfully adopted in the conceptual design of an aircraft version.