An extensively automated optimization procedure is presented for a horizontal axis wind turbine (HAWT) blade based on ultimate limit state analysis. Two composite materials named glass fiber reinforced plastic (GFRP) and carbon fiber reinforced plastic (CFRP) are applied with a multi-objective of blade cost and total mass. Laminate layer thickness, material type and orientation angle are tailored for the structural performance and subjected to three design constraints which are derived from analysis of ultimate strength, fatigue failure and critical deflection, respectively. Combining FEM analysis and an evolutionary algorithm, the proposed optimization process has dramatically reduced design cost and improved blade performance.