家世

乃賈誼九世孫，父親是賈徽。

生平

賈逵從小聰穎過人，其姐為韓瑤之婦，未生孩子。她為人賢明，被人稱道。賈逵隔壁鄰居家中，天天有孩童讀書，賈逵年方五歲，實未到讀書年齡，卻對讀書聲，表現出很大的興趣，賈逵的姐姐便每天抱著他，隔著籬笆，讓他聽隔壁的學童讀書。賈逵總是一聲不吭，靜靜地聽著。

天長日久，賈逵受到了良好的薰陶，到10歲時，他就能背誦《詩經》、《尚書》、《易經》、《禮記》等典籍。他的姐姐沒有想到隔著籬笆聽人讀書，會有這麼好的效果，奇怪地問弟弟道：「我們家貧窮，從來沒有請過教書先生進門，你怎麼知道這麼多古代書籍，而且能一字不漏地背出來呢？」賈逵告訴姐姐說：「起初姐姐抱我在籬笆旁聽鄰居孩子讀書，我便記住了，所以如今能一字不差地全背誦起來。」賈逵曾經將庭院中的桑樹皮，剝下來當紙，隨時記錄書中詞句，或者將字寫在家中門窗、屏風等上面，一面背誦，一面記錄。一年以後，經文全都精通了。

成年的賈逵身形高大，長八尺二寸。弱冠能誦《左傳》、《五經》之說，以《大夏侯尚書》教授，諸儒稱之：「問事不休賈長頭。」。建初四年（79年），賈逵參加了漢章帝在洛陽召開的白虎觀會議，與李育 (儒家)辯論。漢明帝時任為郎。漢和帝時任左中郎將，遷侍中，領騎都尉。他倡導用黃道坐標測量日月行度，並對月行遲疾規律有深刻認識，主張曆法必須不斷改進，提出鼕至點移動。

所著共百萬言，又作詩、頌、沫、書、連珠、酒令凡九篇。永元十五年（103年）創製黃道銅儀，並提出月球運行速度不平均，即「月行有遲疾」，「乃由月所行道有遠近出入所生，率一月移故所疾處三度，九歲九道一複」，也就是最進點每九年運動一周，這實際上正是拱線運動的結果。後世稱「通儒」。《後漢書》論曰：「鄭、賈之學，行乎數百年，遂為諸儒宗。」卒于永元十三年（101年；或100年）。

著作

主要著有《春秋左氏傳解詁》三十篇、《國語解詁》二十一篇、《左氏傳大義長於二傳三十事》、《歐陽大小夏侯尚書古文同異》三卷、《齊魯韓詩與毛詩異同》與《周官解詁》等，皆已亡佚。故凡有所說皆依《後漢書．鄭范陳賈張列傳》（卷三十六）。

後世研究

依宋代王應麟始有從事於蒐輯賈逵著作為《賈氏左傳佚說》，可見在宋朝時已皆不可見賈逵的作品了。現在我們所可察見賈逵之學說大要，主要從清儒黃奭、王漠、馬國翰三家的賈氏遺作輯本，而余蕭客，嚴蔚、馮明貞亦收賈氏佚說。這其中以馬國翰《玉函山房輯佚書》及嚴蔚《春秋內傳古注輯存》及馮明貞《補輯》所輯尤多，而賈逵之遺說亦可見其更概。依此清儒輯佚及史志目錄，賈逵著作至少有下列數種，包括《春秋左氏長經章句》二十卷、《春秋釋訓》一卷、《毛詩雜難》十卷等。

注釋

Zuo Zhuan expert

Like his father, Jia Hui, he was an expert in the Zuo Zhuan and the Guoyu, presenting his commentary on these to Emperor Ming in around 67 CE, who added them to the imperial collection. He was a colleague of Ban Gu at the imperial library, and like him, wrote a commentary on Qu Yuan's poem Li Sao.

Writings

Upon Emperor Zhang's ascension to the throne, he ordered Jia to write of the Zuo Zhuan's superiority to both the Guliang Zhuan and the Gongyang Zhuan. Jia produced the work, arguing that only Zuo Zhuan agreed with the supposedly-prophetic chen, proclaiming that the House of Liu (the Han dynastic family) was destined to rule as successors of the legendary Emperor Yao. Impressed by the result, the emperor then commanded Jia to select twenty scholars then studying the Gongyang Zhuan, instruct them in the Zuo Zhuan and compile a new edition and commentary.

Around 82 CE, he completed three more works in which he compared the "New Text" and "Old Text" versions (i.e. those saved from the Qin book burnings by Fu Sheng and those discovered in a wall of Confucius' estate and transcribed by Kong Anguo) of the Book of Documents, Rites of Zhou and the Classic of Poetry.

Writings and poetry

According to Jia's biography in the Book of the Later Han, he wrote over a million words commentary on the Confucian classics, as well as poetry.

Jia was commissioned in 85 CE to produce a report on the fine-tuning of the amended and re-introduced Sifen calendar.

Under Emperor He, he was promoted to General of the Household in 91 CE, and Commandant of the Cavalry in 97 CE. He died in 101 CE, aged 71.