Abstract: To study the acoustic characteristics of open-plan offices under Chinese language environment and the relationships between subjective evaluation and objective indices,measurements were made in four open-plan offices in Beijing,along with a series of questionnaires surveys.The results show that,acoustic quality is the second important factor for such office environment,just after lighting,and there is a certain degree of requirement for speech privacy. Although subjective evaluation of the acoustic environment depends on the type of work,it is generally between "neither good nor bad" and "bad".The subjective evaluation significantly correlates to L_Aeq and L₁₀,so that using reverberation time only is not appropriate to evaluate the acoustic environment.Reducing speech transmission index could considerably improve the speech privacy as well as the overall acoustic evaluation.Subjective factors including the recognition of acoustic environment,loudness sensitivity,and emotional feeling based on mood and tiredness,significantly affect the acoustic environment evaluation,whereas no significant influence has been found from the concentration level on work, working hours per day,age,income and position.