In this work,the forms and availability of Cu,Zn,Mn and Fe of principal agricultural soils in Gansu Province were studied.The results showed that the contents of Cu,Zn,Mn and Fe in the experimental soils were 22-24mg/kg,73-74mg/kg,542-772mg/kg and 25685-38355mg/kg respectively.Of the four soil types tested the contents of Cu,Zn,Mn and Fe were the lowest in irrigated desert soil but the highest in cinnamon soil.Most of Cu,Zn,Mn and Fe in the soil occur in residual mineral form and bound to iron oxide (amorphous and crystalline).Both biological experiment and statistical analysis pointed that the exchangeable form and the form loosly bound to organic matter were the most available forms of Cu,Zn,Mn and Fe for plants.