A polarization multiplexing duobinary free space optical access system is designed for the special terrain and landform access application in the Three Gorges reservoir ar ea.Under good weather conditions,10Gb/s polarization multiplexing duobinary signals can be successful ly transmitted over the 1km free space optical wireless link.Tested the optical spectrums,eye diagrams and bit error rate before and after transmission of two polarization multiplexing duobinary signals in thi s system.The results show that the receiving eye diagrams of the 10Gb/s polarization multiplexed duobinar y signal transmitted through the 1km free space optical wireless channel in sunny conditions is clearly visib le,the signal reception quality is high,and under the condition of 10-6 bit error rate,the optimal dem odulation decision points of the two data signals demodulated and restored after polarization demultiplexi ng are 0.5bit and 0.51bit respectively,the sensitivity of this system receiver is －2.7dBm,so the access system scheme has good transceiver and transmission performance.Compared with conventional access meth ods,the scheme can not only effectively improve the optical spectral efficiency of the transmitted sign als within the limited bandwidth,but also realize the free space high-speed wireless signals transmis sion within the "last 1km access" in the Three Gorges reservoir especially geom orphologic area.