Abstract: ThO 2 is irradiated with 60 MeV/u 18 O beams. 230 Ra is produced via the multi nucleon transfer and dissipative fragmentation reactions of the target. 230 Ra is radio chemically separated from ThO 2 and the other reaction products. The thin Ra sources are prepared. The mica fission track detectors are exposed to the Ra sources. γ Rays of Ra decay in the sources are measured by a HPGe detector. The mica foil is etched in HF solution. The etched mica foil is scanned with an optical microscope. The fission tracks that should come from β delayed fission of 230 Ac are observed. The β delayed fission probability of 230 Ac is determined to be (1.19±0.85)×10 -8 .