Abstract: According to requirements of the lunar sampling return mission,the lunar ascent trajectory optimization and some of influence factors for the fuel consumption are studied. Based on the ascent motion equations,the trajectory optimization model for optimal fuel consumption with orbit insertion constraints is constructed and then the optimal control of the thrust direction is solved by the Gauss pseudospectral method and the sequential quadratic programming. Using the ascent motion equations with different initial thrust to weight ratio and terminal constraints with different orbit insertion parameters,relevant results on the fuel consumption are acquired by solving the relevant trajectory optimization model and the effects of these parameters on the fuel consumption are analyzed. Three schemes for the non-coplanar ascent,i. e. the yaw steering in ascent,the ascent node maneuver on orbit and the inclination maneuver on orbit,are proposed and the applicable situations are analyzed respectively in term of the fuel consumption.