大成门，又名戟门，是孔庙的第二进院落的正大门。大成门虽然称为门，但是其形制却像是殿堂，是一种身份地位的显示。《唐志》中规定“三品以上官员，可私立门戟”，由此可见，孔庙高立大成门，实际是孔子在古代帝王心目中地位的显示。
大成门是一座面阔三间、进深五檩带周围廊之单檐歇山顶木构建筑．它立于台基之上，台基高出地面0.3米， 面阔15.2米，进深8.2米，正中设垂带踏跺3级。大成门通面阔14. 1米，通进深7.1米，殿高8.15米，共用柱12根。屋顶正脊两端各立有一只龙头鱼身的“螭吻”，具有镇火及独占鰲头的象征。明间置有抱鼓石，开穿堂门，门上装饰铺首和门钉。
大成门悬挂着清雍正七年（1729年）雍正帝御书的“大成门”匾额和“先觉先知为万古伦常立极；至诚至圣与两间功化同流" 楹联。楹联以极其精准的语言道出了孔子的伟业和功绩。其义为先知先觉的孔子，为千秋万代的伦理道德树立了标准法则；道德高尚的孔子，有培养教化天地万物的功德。
Dacheng Gate is the entrance to the second compound of Confucius Temple. Though called a gate, it looks more like a stately hall that embodies the Confuciusstatus in the minds of ancient emperors. This wooden structure has single-eave gable-on-hip roofs. Lying on a longer pedestal above the ground, it features 12 columns and each end of the front ridge has a dragon-beak decoration. There is a drum-shaped stone in the outer room and the room has a door decorated with ring-handles and door nails. Overall, 14.1 m length, 7.1 m width and 8.15 m height make it somewhat an edifice. Above the gate is hung a tablet inscribed with the gate name, flanked by both lines of a couplet:
“The prescient master has enacted a set of moral codes for aeons; this lofty thinker did enlighten all beings in the world.” These words depict well the Master’s merits.
