| Challenger Zhuhai Qual | 03/05 03:50 | 45 | Файджинг Сун v Ruikai Wang | 6-1,6-4 | |
| ITF China F3 | 02/29 04:30 | 25 | Файджинг Сун v Габриел Пети | 2-6,1-6 | |
| ITF China F2 | 02/25 03:45 | 26 | Enrique Lopez-Perez v Файджинг Сун | 6-2,6-4 | |
| ITF China F2 | 02/23 03:20 | 25 | Файджинг Сун v Neven Krivokuca | 7-6,3-6,7-6 | |
| ITF China F1 | 02/17 03:25 | 25 | Вишая Тронгчароенчайкул v Файджинг Сун | 6-2,2-6,7-5 | |
| Чалънджър - Шанхай | 10/10 05:35 | 45 | Файджинг Сун v Го Соеда | 0-6,0-6 | |
| ITF China F13 | 08/11 04:30 | 25 | Xiao Gong v Файджинг Сун | 6-2,7-6 | |
| ITF China F12 | 08/03 08:00 | 25 | Шо Катаяма v Файджинг Сун | 6-4,6-4 | |
| ITF China F11 | 07/21 02:00 | - | Файджинг Сун v Риота Танума | 6-3,4-6,4-6 | |
| ITF China F10 | 07/14 02:00 | - | Файджинг Сун v Зе Жанг | 1-6,5-7 | |
| ITF China F9 | 07/02 02:00 | - | Же Ли v Файджинг Сун | 6-3,6-1 | |
| ITF China F9 | 06/30 09:35 | - | Zhicheng Zhu v Файджинг Сун | 3-6,4-6 | |
| ITF China F8 | 06/23 04:45 | - | Ксин Гао v Файджинг Сун | 6-1,6-3 | |
| ITF China F6 | 06/02 02:00 | - | Куан-Йъ Ли v Файджинг Сун | 6-3,6-2 | |
| ITF China F6 | 05/28 02:00 | - | Же Ли v Файджинг Сун | 6-3,6-1 | |
| ITF China F6 | 05/19 02:00 | - | Файджинг Сун v Же Ли | 1-6,2-6 | |
| ITF China F4 | 04/25 02:00 | - | Файджинг Сун v Чеонг-Еу Ким | 2-6,2-6 | |
| ITF China F4 | 04/24 02:00 | - | Файджинг Сун v Же Ли | 6-4,6-1 | |
| ITF China F4 | 04/23 04:40 | - | Yuqing Ning v Файджинг Сун | 6-7,4-6 | |
| ITF China F4 | 04/21 06:35 | - | Рет Пърсел v Файджинг Сун | 2-6,6-4,2-6 | |
| ITF China F4 Qual | 04/20 02:30 | - | Аоран Уанг v Файджинг Сун | 6-7,6-7 | |
| ITF China F4 Qual | 04/19 02:00 | - | Patrick Ogier v Файджинг Сун | 2-6,1-6 | |
| ITF China F2 Qual | 04/16 02:00 | - | Цунг-Хуа Янг v Файджинг Сун | 6-3,6-3 | |
| ITF China F2 Qual | 04/12 05:15 | - | Zhuoyang Qiu v Файджинг Сун | 4-6,1-6 | |
| ITF China F2 | 04/09 02:00 | - | Файджинг Сун v Ян Бай | 2-6,2-6 | |
| ITF China F2 | 04/07 03:40 | - | Su Hao Zhong v Файджинг Сун | 1-6,0-6 | |
| ITF China F2 Qual | 04/06 02:00 | - | Файджинг Сун v Zhuoyang Qiu | 6-1,6-3 | |
| ITF China F2 Qual | 03/30 03:35 | - | Файджинг Сун v Liang-Chi Huang | 6-7,1-6 | |
| ITF USA F6 | 01/25 15:30 | - | Александър Ротсерт v Файджинг Сун | 5-7,7-6,6-3 | |
| ITF USA F6 | 01/24 19:00 | - | Файджинг Сун v Yuanfeng Li | 7-5,6-1 |
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.