In order to achieve full light utilization and satisfy the demand for far-field illuminance of LED, automated optimization method in sequential mode of ZEMAX was proposed in the design of collimator with far-field illuminance for LED source. The system was established in ZEMAX′s multiple configurations, and the user defined merit function was written out using ZEMAX Programming Language (ZPL) macros language. In the simulation, the material of lens is PMMA and the source is Lambertian-type LED light source, of which divergence angle is 180°. Optimum parameters of collimator were obtained via running an optimization. The optical simulation results show that an efficiency of 87% is achieved under a view angle of ±0.1° and for a point LED source.