F²⁺ beam with 3 MeV is used to irradiate thin biological samples (onion inner surface membrane and kidney bean coat) in the transmission measurement, its current density is 400~800 nA/cm². Results show that the onion samples can be broken up quickly under ion irradiating; as to kidney bean samples, about 60% of the implanted ions penetrate the samples, most of them lose part of their energy, fewer ions are found to be able to transmit through the sample without energy loss. SEM experiments are carried out to study sample's damage induced by the ions irradiation.