Positron beams have been successfully commissioned to the injection point of the BEPCII Linac on 19th March 2005, with an initial beam intensity of 45mA which is one order of magnitude higher than the old BEPC specifications. The success marks another critical step towards the final goal of the BEPCII Linac upgrade. Now the beam energy has reached 1.3 GeV, which is enough to satisfy the requirements of the storage ring for its machine study.

　　Electrons were successfully commissioned to the injection point on 19 November 2004, hence having ensured a dedicated storage ring running for SR and test beams for BESIII between the injections. The positron source commissioning started after the Spring Festival. Taking advantage of the time intervals between the injections for the dedicated SR running, the Linac staff solved many difficulties and problems by carefully examining and testing equipments, in the end they successfully commissioned positrons to the injection point.

　　Currently the Linac staff are continuing their efforts in improving the beam performance and optimizing its quality, working hard to reach the designed value at an early date.