With the rapid development of air transportation industry, many air traffic controllers are facing overload, which brings potential danger to the flight safety. In order to reduce the workload of air traffic controllers, this paper studies sector optimum partition of terminal airspace. Firstly, airspace topology structure is built to describe the relation of key way points, legs and air routes. Power polygon divides the terminal airspace into several units, the workload of each way point can be calculated. Then the sector optimum partition mathematical model is built. A kind of permutation and combination algorithm is used to recombine the units, the objective function value of each unit is regarded as optimization function, and the optimal solution can be worked out in combination with the Particle Swarm Optimization. At last, an example of Beijing Terminal Airspace sector optimum is given, which shows Particle Swarm Optimization is an effective method to be applied into sector optimum partition based on way points workload.