VENUS 1# was the first fast-thermal coupled accelerator driven sub-critical experimental facility of the world built by China Atomic Energy Institute-CIAE. In this paper, the leakage and net neutron yield of fast zone and leakage neutron spectrum driven by 252Cf, Am-Be and D-T neutron sources with different loading layers was calculated based on VENUS 1# unidirectional coupling mode. The results show that, from the view of energy production and transmutation, there exists optimized fuel loadings of fast-zone, which will provide theoretical b...