The Tao Te Ching doesn't jibe with any of the formal meters of Western poetry, so the best term we have for its style is probably free verse. Really, the TTC is the ultimate poetic wild card. It was originally written in Ancient Chinese, which didn't have punctuation. This makes it extra hard (even for modern Chinese speakers) to figure out where thoughts are supposed to stop and start and with what particular rhythm the TTC is meant to be read.
Of course, there are a ton of different English translations out there, some of which make the text more punctuated and/or formally rhythmic than others. But if you ask us, it seems like those versions are missing the point. The cool thing about the original TTC's lack of punctuation is that it makes all the TTC's big ideas flow together. Yeah, it can make the book hard to decipher, but the Tao is pretty hard to decipher too. So, ultimately, the form of the TTC makes total sense, right? The original is just as free-flowin' as the great Tao itself.