In spite of his grumpy and irritable persona, he is highly submissive to the Golden Dragon of Unity.
Though he is the main villain, his role in the film is small. He appears in Qui Gong, where the three princesses' marriages are supposed to take place. However, after an earlier incident involving Shang supposedly dying, Mulan shows up in the princesses' stead and persuades Lord Qin to allow her to marry one of his princes. Qin complies and declares that Mulan will make a perfect bride for his eldest son, Prince Jeeki, after which Jeeki is introduced.
However, before Qin is able to complete the marriage, Shang, who is revealed to be alive and well, arrives in Qui Gong and tries to stop Mulan from going through with the wedding. Qin becomes angered by Shang's unwelcome arrival and his love for Mulan against the intended marriage. When Shang refuses to leave, Qin attempts to have him taken away by the guards, but they are stopped by the Golden Dragon of Unity (actually Mushu imitating the dragon by speaking from inside the statue). After some convincing from the Golden Dragon of Unity, Qin is forced to come to his senses and stop the wedding.
In the aftermath, Mulan and Shang get married, while the Emperor's three princesses are released from their vows and free to marry whomever they please, thus keeping the unity between the two kingdoms intact. Qin is last seen playing with Jeeki's fingertrap, enjoying it.