Abstract: Geometric constraint problem is equivalent to the problem of solving a set of nonlinear equations, and the constraint problem can be transformed into an optimization problem. Inspired by the classical PSO method and quantum mechanics theory, this paper presents a novel quantum-behaved PSO (QPSO) to solve geometric constraint problems. In the QPSO model, the state of a particle is depicted by a wave function instead of position and velocity. The advantage of the algorithm is that it can maintain the diversity of the population in the interested problems. The experimental result shows that the algorithm can improve efficiency and convergence of the geometric constraint solutions.