In this study we carried out field studies in two office buildings in Shanghai, China to investigate the effects of indoor environmental quality on human productivity. The overall perception of occupants on indoor climate (including thermal sensation, perceived air quality, and perceived noise etc.), the influence of human factors and indoor climate factors on productivity, as well as their sick building syndrome (SBS) symptoms were assessed with subjective questionnaires. The building operating cost and employee’s salaries were record objectively. Meanwhile the indoor air temperature, humidity, air velocity, noise, concentration of formaldehyde and carbon dioxide were measured. The results indicate that about 50% occupants complained SBS symptoms when exposed to their office. Most occupants require to increase fresh air and lower the indoor noise level (especially for open-plan office), even though the physical parameters meet the requirement of standards. Thermal environment, indoor air quality and noise assessed to be the three main indoor climate factors that affect human productivity. The employee’s salaries were over 100 times of the electrical energy cost in this two buildings, which indicate great financial benefit can be achieved in China to increase occupants’ productivity by improving the indoor climate.