The complex bilevel programming problem (CBLP) in this paper mainly refers to the optimistic BLP in which the highdimensional decision variables at both levels. A cooperative coevolutionary particle swarm optimization (CCPSO) is proposed for solving the (CBLP), in which the evolutionary paradigm can efficiently prevent the premature convergence of the swarm. Furthermore, the stagnation detection strategy in our algorithm can further accelerate the convergence speed. Finally, we use the test problems from the reference and practical example about watershed water trading decision-making problem to measure and evaluate the proposed algorithm. The presented results indicate that the proposed algorithm can effectively solve the complex bilevel programming problems. c 2017 All rights reserved.Keywords: Complex bilevel programming, cooperative coevolutionary particle swarm optimization, watershed water trading decision making problems, elite strategy. 2010 MSC: 65K10, 90C25.