For the design of variable camber wing of long range wide-body civil aircraft, the trimmed configurations with flap and spoiler deflecting were researched, which can fully consider both the impact on trim characteristic and the feasibility of variable camber wing. The Reynolds averaged Navior-Stokes equations were solved to predict the drag precisely and the Response-surface models were built based on these results. The drag reduction optimizations were carried for multi-conditions with different lift coefficients and Mach numbers. The optimization results show that at cruise mach number, the camber variation can lead drag reduction except at lower lift condition, and at lower mach number the drag can also be reduced by camber variation. The optimal angles of flap for each flight condition are different. Based on the above-mentioned work, the requirement of camber variable manipulation and the general drag reduction were researched by numerical simulation. The results show that two camber settings can lead drag reduction in a large range of lift. The camber designed for cruise condition can still obtain drag reduction at lower mach number. The general profit of cruise efficiency was evaluated based on Breguet equation. When cruising at a fixed altitude of 10km, 1.9 cts of drag reduction and 0.72% increase of flight time and endurance can be obtained during the whole cruise phase. When cruising at stepped altitudes of 8km and 10km, 2.9 cts of drag reduction and 1.19% increase of flight time and endurance can be obtained.