Gaby () is a born coward, a middle-aged office worker who only wants his family to live a carefree and healthy life, while Cheng () is a boy of 19 years old and a born fighter. He always believes in taking control of his own destiny with his fists. As usual, it is speculated that these two people will not intersect in age and life, but fate has tied these two unrelated people together.

Gaby's daughter was bullied. In order to get rid of her daughter's shame, Gaby decided to go outside and talk about it in person. There was a mistake in the confusion. The 40-year-old uncle found Cheng Xi, and he was beaten up by Cheng Xi. When things are understood, the family will know that the bully is not only prominent, but also the champion for two consecutive years. In order to vent their anger on their daughter, the family must summon up courage and decide to worship Chengxi as a teacher. Unable to overcome the uncle's strong demand, Cheng Xi decided to try his best to teach the family, but the condition was that the master-apprentice ceremony must be strictly observed. In the face of this difficult request, the family will not feel embarrassed at all.

How to change Uncle Jia's cowardice with 40 days of summer vacation, the devil training began. In the face of difficult training, the family will be satisfied. How to change uncle Gaby's timid character, Cheng Xi thinks this is the most urgent problem to be solved at present. How to defeat each other mentally? Forty days passed quickly, and the decisive battle was just around the corner. Will Uncle Gaby win?

Fly, Dad, adapted from the novel of the same name by Japanese and Korean writer Kazuki Kaneshiro, tells the story of a 39-year-old timid parent who turned into a hero after learning from a fighter of 19 in the crisis. Realistic action and humorous plot. In the film, Li Junji plays 19-year-old fighting master. This time, he swept away his gentleness and charm, and completely showed people as a cold and fierce real man, showing "Li Kung Fu" for the first time. According to the film, the appearance seems weak, but Li Junji in life is full of masculinity. In order to show his tough guy demeanor, Li Junji specially asked the film to stick a 7 cm long scar on his face, and insisted on using his three-stage taekwondo skills to complete all the fighting scenes, without double body. In addition, Li Junji also trained the role like a devil, climbing cliffs and dodging flying balls. Make yourself strong. In addition, Li Junji himself attached great importance to the debut of Fly Dad in China. "As actors, we must constantly challenge new roles and make changes. Only in this way can fans feel fresh. Maybe someone will get to know me again this time, but I firmly believe that everyone will not be disappointed. "