A first-order simulation is performed on beam optics of the Fudan single-ion microbeam facility

which is designed to irradiate individual living cells at highly localized spatial region with accurately controlled dose.A typical proton beam of 1.5 MeV for routine experiments is simulated.The results of the transporting beam envelope and the beam profile

the phase space and the divergence angles at the end of the beam line show good status(x<0.2 cm

y<0.3 cm;x’<4.8 mrad

y’<6.5 mrad) for extracting a collimated microbeam.Concerning the possible influences of space charge effects

1.5 MeV protons with a beam current up to 7 mA(far higher than common value) is also calculated

the beam size at the end of the beam line can still be focused within 0.6 cm in diameter

with the divergence angles below 6.5 mrad.The results are still good enough for the requirements of a collimated microbeam through the capillary collimator.