With the development of broadband access network, Ethernet Passive Optical Network (EPON) becomes a candidate for fiber to the home. As the huge amount of Optical Network Units(ONUs), the deployment of EPON is affected by the cost of ONU. A low cost EPON (ONU using Bi-directional Optical Sub-Assembly (BOSA) with Flexible Printed Circuit (FPC) was proposed. The FPC-BOSA is mounted directly to the ONU board. Small signal response of FPC was simulated by Finite Element Method (FEM), the results prove that the high speed performance do not degrade. However, there is no individual transceiver module in this proposal, so bit error tester can not be used to test the optical performance. Measurement system using network tester was set up. For the transmitter, the extinction ratio over 10 dB and the average optical power over 1 dBm were obtained from 0℃ to 70℃. For the receiver, the estimated sensitivity achieves -27 dBm.