Chen and Liu never looked back after executing a polished backward pike to take an early lead. They nailed a forward pike with 3 1/2 somersaults for a finals-high 82.80 points to almost clinch the title with two dives left.
Chen has won her four world titles with different partners each time. She has had so many different diving mates that when asked to describe them she needed help to remember all their names.
She said her latest partner "is very young but very adaptable, so I find it very easy to work with her."
Chen won her first world title five years ago when she was just 15, the same age that Liu is now.
"I don't have as much experience as the other divers here," said Liu, who is a champion on her world debut. "But I have learned a lot from Chen Ruolin."
China has won gold in three of four diving events so far at Montjuic Municipal pool, with its picturesque views of the Catalan capital.
Earlier, Li scored 460.95 points from six dives after rallying from a poor start to give the world's pre-eminent diving power its fourth straight and seventh of the past eight world title in the men's 1-meter springboard.
"The competitors were so strong. That I can win this again, I am just so lucky," Li said. "When I was young my coach gave me a video about the Olympic Games in 1992. I remember I have a dream I can stand in this pool.
"So today my dream came true and I won the championship. I feel this pool is amazing. Actually, Spain is very lucky for me. Since 2005, I have been here seven times. It's like here is a second home town. In China, somebody called me 'King of Spain.'"
Four-time European champion Illya Kvasha of Ukraine took silver with 434.30 points, while Alejandro Chavez of Mexico earned bronze with 431.55.
The final was billed to be a battle between Li and Matthieu Rosset of France, who finished 0.5 points behind the Chinese diver in the preliminaries on Saturday.
Rosset entered the fifth round in the lead but blew his entry, allowing Li to take command by completing a difficult inward pike with 2 1/2 somersaults for a single-dive highest score of 86.70.
But with Kvasha pushing, Li still had to execute a tough forward pike with 3 1/2 somersaults on the last dive to ensure he won.
"My coach told me that I need to control myself," Li said. "I knew that in the last rounds I have the confidence that I can overcome everything."
Rosset, who was aiming for France's first diving medal at the worlds, finished in sixth place.
On Saturday, Wu Minxia and Shi Tingmao won the women's 3-meter synchronized springboard. The next day, China's run of three consecutive world titles in the men's synchronized 10-meter platform was broken by German pair Sascha Klein and Patrick Hausding.
