"比喻表达法" can be translated into English as "figurative expression" or more specifically in the context of rhetorical devices, "metaphorical expression".
"Figurative expression" broadly refers to language that uses figures of speech (such as metaphors, similes, etc.) to convey meanings beyond the literal interpretation.
"Metaphorical expression" more precisely emphasizes the use of metaphors, which are a type of figurative language that directly compares one thing to another for rhetorical effect.
In academic or rhetorical contexts, if you want to specifically highlight the use of metaphors, "metaphorical expression" would be more appropriate. However, "figurative expression" is a more general term that encompasses various types of figurative language.