Terahertz　frequency　range　spans　from　0.1　to　10　THz.　Terahertz　radiation　can　penetrate　nonpolar　materials　and　nonmetallic　materials,　such　as　plastics,　wood,　and　clothes.　Then　the　feature　makes　the　terahertz　imaging　have　important　research　value.　Terahertz　computed　tomography　makes　use　of　the　penetrability　of　terahertz　radiation　and　obtains　three-dimensional　object　projection　data.　In　the　paper,　continuous-wave　terahertz　computed　tomography　with　a　pyroelectric　array　detectoris　presented.　Compared　with　scanning　terahertz　computed　tomography,　a　pyroelectric　array　detector　can　obtain　a　large　number　of　projection　data　in　a　short　time,　as　the　acquisition　mode　of　the　array　pyroelectric　detector　omit　the　projection　process　on　the　vertical　and　horizontal　direction.　With　the　two-dimensional　cross-sectional　images　of　the　object　are　obtained　by　the　filtered　back　projection　algorithm.　The　two　side　distance　of　the　straw　wall　account　for　80　pixels,　so　it　multiplied　by　the　pixel　size　is　equal　to　the　diameter　of　the　straw　about　6.4　mm.　Compared　with　the　actual　diameter　of　the　straw,　the　relative　error　is　6%.　In　order　to　reconstruct　the　three-dimensional　internal　structure　image　of　the　straw,　the　y　direction　range　from　70　to　150　are　selected　on　the　array　pyroelectric　detector　and　are　reconstructed　by　the　filtered　back　projection　algorithm.　As　the　pixel　size　is　80　mu　m,　the　height　of　three-dimensional　internal　structure　image　of　the　straw　is　6.48　mm.　The　presented　system　can　rapidly　reconstruct　the　three-dimensional　object　by　using　a　pyroelectric　array　detector　and　explores　the　feasibility　of　on　non-destructive　evaluation　and　security　testing.