Abstract: Optimization design of chiller capacity allocation between the steam double effect Libr unit and electricity-powered chiller has been analyzed in supply cooling system in energy station. And several simulation models had been set up for several typical buildings based on DeST software, and the all-around year hourly cooling load had been calculated. Considering the initial investment and the annual operating cost, the life cycle cost (LCC) method had been adopted to analysis the optimization design of chiller capacity allocation between steam double effect LiBr unit and electricity-powered chiller for the energy station. And the calculated results shown that the optimized LiBr unit ratio is 61.8% in the typical condition. Then, the effects of COP of electricity-powered chiller and steam price on the chiller capacity allocation had been researched, the results shown that the optimized LiBr unit ratio is decrease along with the increase of the COP, and is also decrease along with the increase of the steam price. And this paper can provide the reference for optimization design of chiller capacity allocation for supply cooling system in the similar energy station.