Based on a national three-star greening project，namely the project of office hall design for the adminis-trative committee of Dongguan Eco Park，a series of computer simulations and energy consumption measurements are carried out to analyze and compare the effects of several passive and active energy-saving techniques on the eco performance of office buildings in the South of the Five Ｒidges． The passive energy-saving techniques include the o-rientation optimization as well as the utilization of sunshading，natural lighting and ventilation，and the active ener-gy-saving techniques include water recycling and air conditioning supported by water source heat pump． Then，a priority of the aforementioned passive techniques with less technological demand but greater efficiency，as well as an auxiliary use of the active energy-saving techniques to meet the requirements in particular conditions，is sugges-ted，which helps to improve the eco performance and reduce the energy consumption of office buildings．