In order to study the deformation and bearing characteristics of first-order variable diameter pile under vertical load，a set of first-order variable diameter piles and equal diameter piles were selected for comparative static load test. This test made an analysis by comparing the axial force distribution curve of the pile body，the stress at the pile end and the stress variation curve at the variable section，the pile side frictional resistance a- long the pile body distribution curve and the pile top P-S curve. The results showed that the first-order vari- able-section piles had higher efficiency per unit volume of material，8% higher than that of equal diameter piles. The load transfer of the variable-section piles was still dominated by the lateral friction. When the soil layer was weak at the variable section，it softened at the variable diameter as the load increased，and the resistance at the variable diameter tended to be stable，with limited function.