| ITF Uzbekistan F1 | 04/16 09:00 | 25 | [330] スン・ファジン v ロマン・サフィウリン [381] | 2-6,4-6 | |
| ITF Qatar F3 | 03/15 11:30 | 27 | スン・ファジン v ダニエル・アルトマイアー | 1-6,3-6 | |
| ITF Qatar F3 | 03/14 12:00 | 26 | スン・ファジン v ドミニク ケロフスキー | 6-1,6-4 | |
| ITF Qatar F3 | 03/13 12:00 | 25 | スン・ファジン v ムサ・シャナン・ザイード | 6-1,6-0 | |
| ITF Qatar F2 | 03/08 14:45 | 27 | スン・ファジン v マルセル・イルハン | 4-6,0-6 | |
| ITF Qatar F2 | 03/07 13:05 | 26 | スン・ファジン v アダム・エ・ミダウィ | 6-1,6-1 | |
| ITF Qatar F2 | 03/06 15:40 | 25 | スン・ファジン v AL Mutawa, Jabor | 6-0,6-1 | |
| Qatar F1, Singles | 03/03 13:00 | 29 | グリェクスポーア,スコット v スン・ファジン | 6-4,6-3 | |
| Qatar F1, Singles | 03/02 12:00 | 28 | スン・ファジン v オマール・ジャカローネ | 6-1,2-6,6-4 | |
| Qatar F1, Singles | 03/01 12:00 | 27 | スン・ファジン v ロンドーニ,ピエトロ | 6-1,6-0 | |
| Qatar F1, Singles | 02/28 12:00 | 26 | スン・ファジン v ジーズー・ベアス | 6-1,7-6 | |
| Qatar F1, Singles | 02/27 12:00 | 25 | スン・ファジン v フレッド・シモンソン | 7-5,6-2 | |
| ITF Hong Kong F5 | 12/25 02:00 | 25 | Hu, Nicholas S v スン・ファジン | 6-4,6-4 | |
| Hong Kong F4, Singles | 12/19 03:35 | 25 | [495] スン・ファジン v 柏 衍(バイ・イェン) [444] | 3-6,2-6 | |
| ITF Thailand F12 | 12/13 03:00 | 26 | [172] アレクセイ・ヴァトゥーチン v スン・ファジン [488] | 6-1,6-3 | |
| ITF Thailand F12 | 12/12 03:00 | 25 | マッテオ・マルティノ v スン・ファジン | Retired | |
| ITF Thailand F11 | 12/05 07:40 | 25 | [495] スン・ファジン v 徳田 廉大 [487] | 3-6,3-6 | |
| ITF Thailand F10 | 11/29 04:30 | 26 | スン・ファジン v Niesten, Miliaan | 1-6,4-6 | |
| ITF Thailand F10 | 11/28 04:55 | 25 | スン・ファジン v アビナフ・サンジブ・シャンムガム | 6-1,6-4 | |
| Suzhou, China | 10/23 04:00 | 25 | [125] チアゴ・モンテイロ v スン・ファジン [499] | Retired | |
| 寧波、中国 | 10/16 04:45 | 25 | [499] スン・ファジン v ピーター・ポランスキー [123] | 2-6,6-7 | |
| 上海、中国、予選 | 10/07 07:15 | 45 | [60] ニコロズ・バシラシビリ v スン・ファジン [494] | 6-3,7-6 | |
| ATP Beijing Qual | 09/30 06:30 | 45 | [76] ダルシス,スティーヴ v スン・ファジン [493] | 6-4,6-2 | |
| ATP Chengdu Qual | 09/23 07:40 | 45 | [120] ステファノス・チチパス v スン・ファジン [491] | 6-4,6-2 | |
| チャレンジャー上海 | 09/12 04:45 | 25 | [491] スン・ファジン v デイン ケリー [284] | 3-6,1-6 | |
| チャレンジャー張家港 | 09/06 05:00 | 25 | [472] スン・ファジン v マティアス・バッキンジャー [296] | 3-6,2-6 | |
| 成都、中国 | 08/01 03:35 | 25 | [402] スン・ファジン v エフゲニー・ドンスコイ [124] | 6-7,2-6 | |
| Challenger Chengdu Qual | 07/29 03:20 | 46 | スン・ファジン v Peng, Hsien-Yin | Walkover | |
| ITF China F13 | 07/22 03:45 | 28 | スン・ファジン v 福田 創楽 | 4-6,6-2,3-6 | |
| ITF China F13 | 07/21 03:30 | 27 | スン・ファジン v Hung, Jui-Chen | 6-2,6-1 |
Sun Fajing (Chinese: 孙发京; pinyin: Sūn Fājīng; Mandarin pronunciation: [swə́n fá tɕíŋ]; born 3 October 1996) is a Chinese tennis player.
Sun has a career high ATP singles ranking of world No. 351 achieved on 10 February 2020. He also has a career high ATP doubles ranking of world No. 181 achieved on 26 February 2024. He has reached 13 career singles finals posting a record of 5 wins and 8 losses, all coming on the ITF Futures tour. Additionally, he has reached 31 doubles finals posting a record of 16 wins and 15 losses, which includes 2 ATP Challenger Tour doubles titles.
Sun made his ATP main draw debut at the 2016 Chengdu Open, where he was granted a wildcard entry in the doubles draw alongside compatriot He Yecong. They were defeated in the first round by Raven Klaasen and Rajeev Ram in straight sets 4–6, 5–7.
The following year, he was again given a wildcard at the 2017 Chengdu Open with partner Te Rigele, and again he would lose in the first round to Nenad Zimonjic and Santiago Gonzalez in straight sets 4–6, 4–6.
In his third main draw appearance, he and partner Zhizhen Zhang were given a wildcard entry into the doubles draw of the 2018 ATP Shenzhen Open but lost in the first round to Marcin Matkowski and Nicholas Monroe 4–6, 2–6.
His fourth and most recent ATP appearance (also his third at the tournament) was a wildcard entry into the doubles draw of the 2019 Chengdu Open pairing up with Wang Aoran, and to round up an 0–4 record he lost to Dominic Inglot and Austin Krajicek 1–6, 6–0, [8–10].
He was given a wildcard at the 2023 China Open (tennis) partnering Zhou Yi (tennis). He received also a wildcard in doubles partnering Li Zhe (tennis) at the 2023 Rolex Shanghai Masters.