The　delta-robot　3D　printer　adopts　the　frame　structure　of　delta-robots.　It　has　three　vertical　beams　which　are　the　supporting　parts　of　the　motion　and　frame　mechanism.　The　pose　of　the　vertical　beams　is　an　error　source　and　has　the　influence　on　3D　printing　precision　and　printing　quality.　The　effect　of　such　error　source　on　the　3D　precision　and　quality　is　random　and　difficult　to　be　captured　by　measuring　instruments.　To　reveal　the　mechanism　of　3D　printing　error　caused　by　the　pose　of　vertical　beams,　through　the　simulation　of　parallel　motion　mechanism　and　the　derivation　of　non-ideal　parallel　printing　model,　the　mechanism　of　error　generation　and　the　influence　of　error　source　on　3D　printing　precision　are　studied.　The　simulation　results　show　that　the　tilted　vertical　beams　can　indeed　cause　the　3D　printing　error　and　further　affect　the　3D　printing　quality,　and　that　the　printing　error　is　related　to　the　size　and　direction　of　the　rotation　angles　of　the　vertical　beams.