We　presented　an　automatic　method　for　detecting　and　tracking　colloidal　gold　fiducial　markers　for　alignment　in　electron　tomography　(ET).　The　second-order　derivative　of　direction　was　used　to　detect　a　fiducial　marker　accurately.　The　detection　was　optimized　to　be　selective　to　the　size　of　fiducial　markers.　A　preliminary　tracking　result　from　the　normalized　correlation　coefficient　was　refined　using　the　detector.　A　constraint　model　considering　the　relationship　among　the　fiducial　markers　on　different　images　was　developed　for　removing　outlier.　The　three-dimensional　positions　of　the　detected　fiducial　markers　and　the　projection　parameters　of　tilt　images　were　calculated　for　post　process.　The　accuracy　of　detection　and　tracking　results　was　evaluated　from　the　residues　by　the　software　IMOD.　Application　on　transmission　electron　microscopic　images　also　indicated　that　the　presented　method　could　provide　a　useful　approach　to　automatic　alignment　in　ET.