(See the discussion of iambic pentameter in the "Writing Style" section of our guide to the General Prologue & Frame Story.)
"The Knight's Tale" is written in a very "high" style, which just means that it uses lots of noble, courtly themes and language. Two of Chaucer's favorite poetic techniques in this story are preterition and ekphrasis. Big words, but don't be scared.
Preterition is just telling an audience something by saying that you're not going to tell them about it. A good example of this from "The Knight's Tale" occurs when the narrator describes Arcite's funeral. Instead of just describing it, he says, "[It] shall nat be toold for me" (2066), then goes on to describe (at great length) all of the things he won't describe. This case of preterition is so ridiculously long that it almost becomes comical, like the narrator is making fun of himself.
Another highbrow poetic technique "The Knight's Tale" uses is ekphrasis, which is the lengthy, dramatic description of a work of visual art in writing. The narrator tells the audience all about the paintings on the walls of the temples of Venus, Mars, and Diana. We get to hear a story-within-a-story as the narrator recounts the paintings of lovers and warriors that decorate these temples.