To　improve　the　performance　of　a　micrometer　inductive　sensor,　a　design　method　of　solenoid　coils　was　put　forward　based　on　the　theory　of　Helmholtz　coils　to　improve　the　uniformity　of　the　axial　magnetic　field　of　a　solenoid　coil.　Firstly,　the　model　of　the　solenoid　coil　was　analyzed　and　the　generalized　function　model　between　the　parameter　of　solenoid　coil　and　the　axial　magnetic　field　intensity　distribution　was　established.　Then,　the　system　function　model　for　axial　magnetic　field　intensity　distribution　was　determined　based　on　the　parameters　of　the　core　and　coil　sizes,　the　minimum　error　objective　function　of　the　uniformity　for　the　magnetic　field　was　set　from　the　core　moving　range,　and　the　best　parameters　of　solenoid　coil　by　objective　function　optimization　were　obtained.　Finally,　a　test　system　for　the　micrometer　inductive　sensor　was　established　to　get　its　detection　performance.　The　test　results　show　that　modified　solenoid　coil　improves　the　linearity　from　0.42%　to　0.25%　in　100　μm　measurement　range　as　compared　with　the　original　solenoid　coil.　It　concludes　that　the　modified　solenoid　coil　uniforms　the　intensity　distribution　of　the　axial　magnetic　field　and　enhances　the　measurement　accuracy.　©,　2015,　Chinese　Academy　of　Sciences.　All　right　reserved.