In this report, the radiological survey of radioactivity measurements in soil and onion and their mobility is carried out which is very important in the environment and several scientific fields. The measurements about the concentrations of activity in soil, leaves and bulbs for onion in the location of Johor and Perak, Malaysia have been carried out using neutron activation analysis (NAA) of TRIGA MARK II research reactor facilities at Nuclear Agency, Bangi, Malaysia. The transfer factors (TFs) of 238U, 232Th and 40K from 6 different natural background soils are studied from soil to onion under natural field conditions. The TFs for onion leaves and bulb are in the range of (6.01-79.2) x 10-3, (1.21-61.4) x 10-3, (1.012-4.265) x 10-1 and 0.028-0.334, 0.017-0.293 and (0.908 -3.685) x10-1for 238U, 232Th, and 40K respectively. There exists a linearity correlation between the dose rate as well as activity concentration of the soils. The observed transfer factor of onion bulbs was usually higher than in leaves.